(Hypertension. 1999;33:569-574.)
© 1999 American Heart Association, Inc.
Scientific Contributions |
Mechanics and Composition of Human Subcutaneous Resistance Arteries in Essential Hypertension
From the MRC Multidisciplinary Research Group on Hypertension, Clinical Research Institute of Montreal, Montreal, Quebec, Canada
Correspondence to Ernesto L. Schiffrin, MD, PhD, FRCPC, Clinical Research Institute of Montreal, 110 Pine Ave W, Montreal, Quebec, Canada H2W 1R7. E-mail schiffe{at}IRCM.Umontreal.ca
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Abstract |
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Abstract—Mechanical properties of arteries are altered in some rat models of hypertension, and this may influence peripheral resistance and blood pressure as well as some of the complications of hypertension. It has usually been assumed that arterial wall stiffness is increased in hypertension, although recent studies suggest that this may not necessarily be the case in large arteries. We determined whether the mechanics of human resistance arteries are altered in hypertension. Subcutaneous resistance arteries (lumen diameter<300 µm) were isolated from hypertensive and normotensive subjects of similar ages (46±3 and 43±4 years, respectively). Vessels were mounted in a pressurized myograph, deactivated, and exposed to intraluminal pressures ranging from 3 to 140 mm Hg. At each pressure, lumen and media dimensions were measured. Media-to-lumen ratio and media width were greater in hypertensive vessels, reducing wall stress (P<0.01), whereas media cross section was similar in vessels from both groups. Isobaric elastic modulus (which is influenced by vessel geometry and by wall component stiffness) was lower in hypertensive vessels (P<0.01). Stiffness of wall components (slope of incremental elastic modulus versus stress, which is geometry-independent) was significantly lower in hypertensive vessels (8.2±0.7) versus normotensive vessels (11.0±1.0, P<0.05), whereas distensibility was unchanged. Electron microscopic analysis of the media of the small arteries showed a greater collagen to elastin ratio (P<0.05) in the media of vessels from hypertensive patients. In conclusion, the stiffness of wall components (slope of elastic modulus versus stress) is not increased but is in fact decreased in subcutaneous resistance arteries from patients with mild essential hypertension. Reduced stiffness of resistance arteries from hypertensive patients does not appear to relate to changes in volume density of extracellular matrix components but may be the result of changes in extracellular matrix architecture or cell-matrix attachment, which remains to be established.
Key Words: arteries, small • remodeling • elasticity • elastic modulus • collagen
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Introduction |
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The structure1 2 and mechanical properties3 4 5 of arteries are altered in hypertension. In large arteries it has usually been assumed that structural changes result in increased stiffness of vessels. It has been shown, however, that this is not necessarily the case. Indeed, several recent studies demonstrate that compliance of large arteries is not uniformly reduced in hypertension and may even be increased.6 7 In experimental hypertensive models in the rat, the structure of small resistance size arteries is altered,1 2 and some studies have shown that in some vascular beds, this is associated with reduced rather than increased stiffness of the vessel wall.8 9 The structural alterations of small arteries may comprise a combination of growth (characterized by increased media thickness and cross-sectional area) and eutrophic remodeling (characterized by decreased lumen and external diameter, with unchanged media cross-sectional area).10 The changes in composition of small arteries may influence how the structural alterations result in changes in wall mechanics. In small arterioles of the cerebral circulation, genetic hypertension is associated with increased elastin and distensibility,11 whereas in the mesenteric circulation, there is increased collagen deposition, without a change in volume density.12
Alterations in small artery mechanics may exacerbate vascular damage resulting from hemodynamic changes (for example, pulse pressure, wave reflection, and shear stress). An understanding of the former provides important mechanistic information for choosing therapeutic targets in hypertension. Mechanical properties may also provide a parameter that may eventually be useful for the noninvasive evaluation of cardiovascular risk. Some studies of human resistance arteries in which their structure has been elucidated in hypertensive patients are available,13 14 but little is known of the mechanical changes that follow the alterations in structure that occur in hypertension. Changes in wall mechanics (stiffness) of resistance arteries may influence pressure-diameter relationships of blood vessels. We hypothesized that as in rat models of hypertension, mechanical properties of human resistance arteries from patients with mild hypertension would not present abnormal stiffness despite altered structure. There is only one previous study in which mechanical properties of resistance arteries from patients with mild hypertension have been studied.15 It showed similar stiffness of wall components in resistance arteries from normotensive subjects and hypertensive patients, but that study was performed with the older technique of the wire myograph. There have been suggestions that the wire myograph may not accurately reflect properties of small arteries,16 although most of the data obtained with the wire myograph in studies of human small arteries have been reproduced in studies using more modern and physiological pressurized arteriographs.17 Therefore, to assess the mechanical properties of pressurized small arteries, we isolated small vessels (lumen diameter<300 µm) from gluteal subcutaneous biopsies performed on normotensive and hypertensive subjects and investigated their mechanics on a pressurized arteriograph. To understand mechanistically changes found in mechanical properties, we investigated the composition of the media of these resistance vessels by electron microscopy.
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Methods |
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Subjects
The protocol was approved by the Ethics Committee of the Clinical Research Institute of Montreal. Written informed consent to participate in the study was obtained from each subject. Subjects aged 25 to 65 years were recruited from the Hypertension Clinic of the Clinical Research Institute of Montreal if they had essential hypertension and had never been treated with antihypertensive drugs. The hypertensive subjects had a history of recumbent systolic blood pressures of >140 mm Hg or diastolic blood pressure >95 mm Hg on more than two occasions. The diagnosis of essential hypertension was established by the absence of clinical evidence of secondary hypertension; normal serum electrolytes, creatinine, and urinalysis; normal abdominal ultrasound examination; and where indicated, normal renal scintiscan, renal arteriogram, and computed abdominal tomography. Individuals were excluded if they smoked more than 5 cigarettes per day, their fasting blood glucose level was abnormal, their serum creatinine concentration was >150 µmol/L, or they had any other systemic disease. Control subjects were recruited simultaneously with the hypertensive subjects and were matched for age. They had systolic blood pressure <140 mm Hg and diastolic blood pressure <85 mm Hg, smoked fewer than 5 cigarettes per day, and had no evidence of disease on physical or routine laboratory investigation. Subjects arrived between 7:30 and 9 AM, having fasted since the previous evening. Blood pressure was measured with a standard mercury sphygmomanometer after subjects had rested 15 minutes in the sitting position. Diastolic blood pressure was read as phase V of the Korotkoff sounds.
Preparation and Study of Pressurized Small Arteries
Biopsies of gluteal subcutaneous fat were obtained from all
subjects by the same physician, with subjects under local
anesthesia. Superficial subcutaneous tissue (1.0x0.5x0.5
cm) was obtained through a horizontal 1-cm-long incision of the skin in
the upper external gluteal quadrant. Arteries were dissected from the
sample of subcutaneous tissue under a dissecting microscope immediately
after the biopsy was obtained, and 1 to 3 small arteries were chosen at
random and isolated. Arteries were mounted in a servo-controlled
pressurized myograph chamber, allowing a stable preset pressure as
previously described.9 The vessels were slipped onto two
glass microcannulas and secured with nylon ties. The axial length of
the vessel was adjusted by moving one cannula until the vessel walls
were parallel without stretch. Vessels were equilibrated under a
constant intraluminal pressure of 60 mm Hg for 1 hour with
physiological salt solution (PSS) (37°C) that was
continuously bubbled with 95% air and 5% CO2 to
achieve a pH of 7.40 to 7.45. PSS contained (mmol/L) NaCl 120,
NaHCO3 25, glucose 5.5, KCl 4.7,
CaCl2 2.5,
KH2PO4 1.2,
MgSO4 1.2, and EDTA 0.026. Vessels were
deactivated of myogenic tone by perfusion with
Ca2+-free PSS containing 10 mmol/L EGTA for
30 minutes. Lumen and media dimensions (for morphology) were measured
while the intraluminal pressure was 60 mm Hg. Intraluminal
pressure was then raised to 140 mm Hg three times, and the
cannula was adjusted until the artery walls were straight and parallel
to each other. Adjustments in length for the maintenance of
parallel walls were minimal.
For calculation of vessel mechanics, intraluminal pressure was increased at several intervals up to 140 mm Hg, as previously described,9 and media thickness and lumen diameter were measured at each pressure level at 5 points along the vessel. The precision of the system was 0.7 µm. The initial diameter was measured at 3 mm Hg unless the vessel collapsed. In these cases, lumen diameter was estimated by fitting the intraluminal pressure-lumen diameter data (measured between 10 and 140 mm Hg) to a third-order polynomial equation.
Determination of the Composition of Small Artery Walls
Composition of the media of small artery walls was studied as we
have previously described.12 Briefly, after morphometric
determinations, pressurized arteries from 5 of the normotensive and 9
of the hypertensive subjects were perfused for 30 minutes with
calcium-free PSS at an intravascular pressure of 60 mm Hg, fixed
with 1.5% glutaraldehyde solution at room temperature
for 60 minutes, and removed from the cannula. After three washes with
calcium-free PSS, vessels were stored in 70% ethanol at 4°C.
Arteries were then fixed with 1% osmium tetroxide for 30 minutes at
room temperature, dehydrated in graded ethanol, and embedded in
araldite CY212 epoxy resin (Ladd Research Industries Inc). Excess resin
was trimmed so that the block face contained only the specimen.
Sections were cut on a microtome (Reichert Ultrathin) at a thickness
ranging from 70 to 90 nm and stained with 0.25% phosphotungstic acid
for 15 minutes, 4% uranyl acetate for 10 minutes, and lead citrate for
3 minutes. The sections were examined with a JEM-1200EX electron
microscope (JEOL Ltd). Electron micrographs were taken at an original
magnification of x4000 and enlarged by a factor of 3 for a final
magnification x12 000. Vessels were divided into four quadrants, and
three electron micrographs were taken randomly for a total of 12 to 15
electron micrographs per vessel. Negatives of micrographs were scanned
(Scan Jet 4C/T, Hewlett-Packard). The areas occupied by smooth muscle,
collagen fibers, and elastin were measured by repeated tracing with a
light pen and then use of an imaging program (Adobe Photoshop 3.0).
Means of repeated tracings recorded in pixels were averaged and
used to calculate the cross-sectional area occupied by each
component.
Data Analysis
Calculation of arterial morphology and mechanics was
done as previously described.9 Results are
represented as mean±SEM. Statistical comparisons were
performed by two-tailed Student's t test. Statistical
evaluation of relationships between mechanical parameters
of vessels from normotensive and hypertensive subjects was performed by
repeated-measures analysis of variance. Where statistical
significance was detected, interaction means were compared using a
two-tailed Student's t test. Differences were considered
statistically significant at a value of P<0.05.
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Results |
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Demographics of the study subjects are shown in Table 1
. Seven normotensive and 14
hypertensive individuals were investigated. The normotensive group had
proportionately more women; otherwise, there were no significant
differences between the groups in age, body mass index, serum
creatinine levels, and serum lipid profile. Blood pressure
was significantly elevated in the hypertensive subjects, who were
untreated at the time of the study.
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The structure of subcutaneous small arteries of the subjects studied is
depicted in Table 2. Media width and
media-to-lumen ratio of the vessels of hypertensive subjects were
increased (P<0.01), whereas media cross-sectional area and
lumen diameter did not exhibit significant differences between the
groups. The growth index, that is, the percent difference in
cross-sectional area of the media between vessels from hypertensive and
normotensive subjects, was 32.8%.
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Vascular mechanics were studied by progressively increasing
intraluminal pressure. The left panel of Figure 1 shows that wall distensibility plotted
against intraluminal pressure was similar in arteries from both groups.
The right panel of Figure 1 depicts the media stress-strain
relationship, which was significantly shallower in the vessels from
hypertensive subjects, indicating that isometric stress was lower in
hypertensive vessels. From the stress-strain relationship, incremental
elastic modulus was calculated and plotted against intraluminal
pressure and circumferential stress (Figure 2). The left panel of Figure 2
shows that incremental elastic modulus plotted against intraluminal
pressure was lower in vessels from hypertensive subjects. The right
panel demonstrates that when plotted against circumferential stress,
the slope of the incremental elastic modulus (ß), which demonstrates
the stiffness of wall components, was significantly lower in vessels
from hypertensive subjects than in those from normotensive subjects.
Since in the present study there was a marked imbalance in the
number of male and female hypertensive subjects, the mechanics of
vessels from male and female normotensive and hypertensive subjects
were evaluated separately. Figure 3 shows
that vessel mechanics in male and female hypertensive subjects were
identical. No significant differences were found between vessels from
male and female normotensive subjects. Differences between mechanics of
all normotensive and hypertensive subjects were thus maintained within
men and women.
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Electron microscopic evaluation of the structure and composition
of the media of pressurized small arteries from 5 of the 7 normotensive
subjects and 9 of the 14 hypertensive subjects showed a trend toward a
greater number of smooth muscle layers (P=0.07) and
higher collagen volume density (P=0.08) in vessels
from hypertensive subjects and a significant increase in the
collagen-elastin ratio (P<0.05) (Table 2
).
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Discussion |
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This study evaluates the vascular mechanics of subcutaneous small resistance size arteries from hypertensive subjects for the first time using a pressurized system, which may represent a more physiological approach than other methods previously used for examining vascular structure and mechanics.17 The composition of the media of vessels was also studied to determine whether changes in the volume density of collagen (less distensible) and elastin or smooth muscle (more distensible) could explain the differences in mechanical properties. We show that subcutaneous small arteries of the hypertensive subjects studied present an altered structure, as previously reported by others13 and in our own studies.14 In this particular group of subjects, media-to-lumen ratio of small arteries was increased, as was media width, whereas media cross-sectional area was not. However, although differences between the media cross section of small arteries did not achieve statistical significance, the growth index was 32.8%, which suggested a trend toward what has been designated as hypertrophic remodeling.10 This finding is in contrast to previous studies from our own group14 and others18 in which the predominant finding was that of eutrophic remodeling, but is in agreement with the first results obtained from the study of human subcutaneous small arteries.13 The heterogeneity of individuals with essential hypertension suggests the need for caution in making our conclusions in view of the range of results that may be encountered.
The lumen diameter of a vessel will depend on opposing forces of
transmural pressure and compliance of the vessel wall. Compliance, that
is, the ability of a vessel to buffer changes in pressure, depends on
the geometry and stiffness of the wall components of the vessel.
Decreases in lumen size (resulting mainly from remodeling in
hypertension10 ) may reduce compliance, which is
geometry-dependent. However, vascular compliance may be normalized by
decreases in elastic modulus. Incremental elastic modulus is
geometry-independent and depends on the stiffness of the vessel wall
components. Elastic modulus is determined by the combined elastic
modulus of the structural components of the vascular wall: connective
tissue, elastin and collagen fibers, smooth muscle cells, and
endothelial cells. Previous studies of the mechanics of
large arteries have demonstrated that vascular wall compliance is not
necessarily reduced in hypertension both in animal models and in human
essential hypertension.6 The mechanism for the absence of
reduced vascular compliance and distensibility despite increased media
thickness and collagen deposition has been obscure. In very small
arteries from the brain, the pioneering studies of Baumbach et
al19 showed for the first time that wall mechanics in
hypertension might not be altered as expected. These investigators
first reported that compliance and distensibility could actually be
increased and that the slope of the incremental elastic modulus in
relation to circumferential stress, that is, the stiffness of wall
components, could be reduced in pial arterioles of approximately
80 µm in lumen diameter from stroke-prone spontaneously
hypertensive rats (SHRSP).8 They found similar results in
small arteries (<150 µm in lumen diameter) but not larger small
arteries (150 to 300 µm in lumen diameter) in the brain. Their
studies demonstrated that the composition of vessels with reduced
stiffness was altered, with increased elastin content,11
which could explain the direction of the alteration in mechanics. We
have found in some groups of SHR,9 and in Dahl-salt
sensitive rats20 and deoxycorticosterone acetate
(DOCA)–salt hypertensive rats,21 similar or lower
stiffness of wall components of mesenteric small arteries than in
equivalent vessels from normotensive rats. Together with
previous6 and more recent22 23 findings in
large arteries from animal models and humans, this may suggest that a
reduced stiffness of wall components is indeed a common characteristic
in hypertension. The mechanism may not be the same for all vascular
beds, however, because in contrast to pial arterioles, in which elastin
is increased, in large arteries in SHR most studies have shown an
increase in collagen deposition24 (although the volume
density of collagen was not increased25 ). In mesenteric
small arteries of SHR we have recently demonstrated increases in
collagen as well.12 In the present study we found that
even though the stiffness of wall components is decreased in vessels
from hypertensive subjects, the volume density of collagen in the media
tends to be increased, although not achieving statistical significance,
and the collagen-elastin ratio is significantly enhanced. This agrees
with our previous findings in mesenteric arteries of similar dimension
in SHR.12 It would be expected that an increased
collagen-elastin ratio might increase stiffness.19 Thus it
is likely that in these vessels other factors are involved, and it is
possible that changes in extracellular matrix–smooth muscle cell
attachments may play a role in the change in mechanical properties
found in both human arteries and those of experimental models of
hypertension. Recent studies have demonstrated that in aorta of SHR,
fibronectin and 
5-integrin are increased.25 It has been
speculated that increases in cell–extracellular matrix attachment
sites may contribute to the maintenance of equivalent
mechanical properties even though SHR vessels, or human vessels in the
present study, are subjected in vivo to higher pressures. The
mechanisms involved in the reduction of the elastic modulus in relation
to wall stress and pressure in resistance arteries from hypertensive
individuals remain unclear. Since differences in the volume density of
more- versus less-distensible components of the media (smooth muscle
and elastin versus collagen) do not appear to play an important role,
the difference in mechanical properties could be related in part to the
characteristics and/or organization of these components in the vascular
wall, particularly the arrangement, alignment, and adhesion of
fibrillar and cellular elements. Models of arrangement of these
components in the vascular wall in general assume that collagen is
arranged in series to smooth muscle cells and in parallel to
elastin.26 The linking of collagen to smooth muscle cells
and the degree to which the collagen jacket is tensed may thus play an
important role, since collagen is less distensible than
elastin.27 Its contribution is supposed to occur in the
latter portion of the pressure curve, since collagen fibers may be
coiled and not under tension until the smooth muscle cells in series
and the elastin in parallel have been stretched. In the remodeled small
artery, with more closely aligned cellular and fibrillar components due
to changes in adhesion of cellular and fibrillar structures, the
collagen fibers may be recruited at higher distending pressures in
vessels from hypertensive subjects than in vessels from normotensive
subjects. Thus, although in small arteries from hypertensive subjects
vascular compliance may be reduced in part because of their smaller
lumen and greater collagen-elastin ratio, this may be compensated by
the engagement of collagen fibers, and resulting tensing of the
collagen jacket may occur in a later portion of the pressure curve.
This has already been proposed by Bank et al28 to explain
changes in compliance and stiffness in the human brachial artery during
contraction and relaxation. If for each level of media stress, elastic
modulus (stiffness) is lower, this will contribute to buffering
the effects of greater intravascular pressure in hypertension.
Elastic properties of subcutaneous small arteries from hypertensive and normotensive individuals have been the subject of one previous study.15 That study was carried out with the wire myograph technique and showed that elastic modulus was not increased in hypertensive vessels. The present results extend the previous observations, showing comparable results with the newer and more physiological approach of examining small arteries in a pressurized system and distending them progressively by increasing intraluminal pressure rather than by stretching the vessels with two wires inserted in the lumen. We have previously demonstrated that structural data obtained with the pressurized system are also comparable to data from observations using wire myography.29 With respect to the study of mechanical properties, both techniques may have limitations. Stretching a vessel with two wires may result in vessel shortening, which may affect the transversally measured elastic properties of the shortened vessel; and pressurization of vessels may result in elongation, which necessitates adjustment of the microcannulas to maintain parallel walls. This could also affect the mechanical characteristics measured. In the present study, however, very little or no adjustment was necessary in the distance between the microcannulas. Thus, it is unlikely that this played a role as a confounder in the results obtained. The loss of tethering by surrounding tissues results in different conditions when the vessels are studied in vitro relative to the in vivo situation. However, the present study does not pretend to examine the in vivo behavior of these vessels, but rather the in vitro characteristics of the vessel wall under similar conditions in arteries from normotensive and hypertensive subjects to help understand the changes that have occurred in the vessel wall. Furthermore, because the original length in vivo of the vessels studied cannot be known, axial stiffness cannot be evaluated whereas circumferential stiffness may be quantified. The arterial wall is anisotropic, that is, direction-dependent.30 Axial and circumferential compliance have been evaluated in carotid arteries in situ in SHR and shown to be similar.31 However, these studies may be performed only when the in vivo length of vessels can be evaluated, such as with the use of ultrasound techniques, which are not yet applicable to the study of human subcutaneous small arteries.17 Because mechanical properties may be altered biaxially,31 32 uniaxial stiffness as investigated in the current study has to be interpreted cautiously.
A limitation of this study is that the proportion of men and
women differed in the normotensive and hypertensive groups. This
resulted from the difficulties inherent in the recruitment of subjects
for an invasive study such as this one, in which a biopsy of
subcutaneous tissue was performed. This could potentially have
contributed to the suggestion of hypertrophic growth in resistance
arteries from this group of hypertensive subjects, who were
predominantly male. However, the stiffness of small arteries from
normotensive men and women was not significantly different, and the
same was found for hypertensive men and women (Figure 3). Also,
within men, the stiffness of vessels was greater in normotensive than
in hypertensive individuals, and in women, the direction of the
findings was similar, although not achieving statistical significance
in the latter because of the small numbers. Thus, although this
imbalance in the number of subjects from each sex is a recognized
limitation, it may not have influenced the results.
The clinical relevance of these findings may result from the fact that altered mechanics of the vascular wall may affect the velocity of the pulse wave, wave reflection, pulsatility of vessels, blood flow velocity, and accordingly shear stress. Vascular wall damage, and with it cardiovascular risk, may be modified by changes in wall mechanics. Decreases in the stiffness of wall components may protect the vessel wall. The extent to which these changes in mechanics are protective and whether their absence may be an indicator of increased vascular risk remain to be determined.
In conclusion, the components of the wall of subcutaneous small arteries of hypertensive subjects are less stiff than in comparable vessels from normotensive subjects. The mechanism for the increased compliance of small arteries of hypertensive individuals remains unclear. The changes found in the composition of the media of the wall of small arteries, an increased collagen-elastin ratio, cannot explain the differences in mechanical properties between vessels from normotensive and hypertensive subjects. It is possible that changes in extracellular matrix architecture or in cell–extracellular matrix attachments may play a role, but this remains to be established. Whether similar changes occur in other vascular beds at the same level of the vasculature requires further study.
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Acknowledgments |
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This study was supported by a group grant from the Medical Research Council of Canada to the Multidisciplinary Research Group on Hypertension and by a grant from the Fondation des maladies du coeur du Québec. Dr. Intengan is supported by a Medical Research Council of Canada/Canadian Hypertension Society postdoctoral research fellowship. The authors are grateful to Mireille Kirouac, RN, and Michelle Lapointe, RN, for help in recruiting subjects for this study and blood sampling.
Received September 16, 1998; first decision October 16, 1998; accepted October 30, 1998.
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  L. A. Martinez-Lemus, M. A. Hill, and G. A. Meininger The Plastic Nature of the Vascular Wall: Reply to Lee, Sandow, and DeMay Physiology, October 1, 2009; 24(5): 273 - 275. [Full Text] [PDF]
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 A. S. Greenstein, A. Price, K. Sonoyama, A. Paisley, K. Khavandi, S. Withers, L. Shaw, O. Paniagua, R. A. Malik, and A. M. Heagerty Eutrophic Remodeling of Small Arteries in Type 1 Diabetes Mellitus Is Enabled by Metabolic Control: A 10-Year Follow-Up Study Hypertension, July 1, 2009; 54(1): 134 - 141. [Abstract] [Full Text] [PDF]
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 R. Dhingra, M. J. Pencina, P. Schrader, T. J. Wang, D. Levy, K. Pencina, D. A. Siwik, W. S. Colucci, E. J. Benjamin, and R. S. Vasan Relations of Matrix Remodeling Biomarkers to Blood Pressure Progression and Incidence of Hypertension in the Community Circulation, March 3, 2009; 119(8): 1101 - 1107. [Abstract] [Full Text] [PDF]
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 F. Feihl, L. Liaudet, B. I. Levy, and B. Waeber Hypertension and microvascular remodelling Cardiovasc Res, May 1, 2008; 78(2): 274 - 285. [Abstract] [Full Text] [PDF]
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G. P. Rossi, M. Bolognesi, D. Rizzoni, T. M. Seccia, A. Piva, E. Porteri, G. A.M. Tiberio, S. M. Giulini, E. Agabiti-Rosei, and A. C. Pessina Vascular Remodeling and Duration of Hypertension Predict Outcome of Adrenalectomy in Primary Aldosteronism Patients Hypertension, May 1, 2008; 51(5): 1366 - 1371. [Abstract] [Full Text] [PDF]
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 X. Wu, Y. Yang, P. Gui, Y. Sohma, G. A. Meininger, G. E. Davis, A. P. Braun, and M. J. Davis Potentiation of large conductance, Ca2+-activated K+ (BK) channels by {alpha}5{beta}1 integrin activation in arteriolar smooth muscle J. Physiol., March 15, 2008; 586(6): 1699 - 1713. [Abstract] [Full Text] [PDF]
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C. Savoia, R. M. Touyz, F. Amiri, and E. L. Schiffrin Selective Mineralocorticoid Receptor Blocker Eplerenone Reduces Resistance Artery Stiffness in Hypertensive Patients Hypertension, February 1, 2008; 51(2): 432 - 439. [Abstract] [Full Text] [PDF]
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 G. Douglas, M. Natalia Cruz, L. Poston, J.-A. Gustafsson, and K. Kublickiene Functional characterization and sex differences in small mesenteric arteries of the estrogen receptor- knockout mouse Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2008; 294(1): R112 - R120. [Abstract] [Full Text] [PDF]
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 K. Sonoyama, A. Greenstein, A. Price, K. Khavandi, and T. Heagerty Review: Vascular remodeling: implications for small artery function and target organ damage Therapeutic Advances in Cardiovascular Disease, December 1, 2007; 1(2): 129 - 137. [Abstract] [PDF]
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 J. M. Gonzalez, A. M. Briones, B. Somoza, C. J. Daly, E. Vila, B. Starcher, J. C. McGrath, M. C. Gonzalez, and S. M. Arribas Postnatal alterations in elastic fiber organization precede resistance artery narrowing in SHR Am J Physiol Heart Circ Physiol, August 1, 2006; 291(2): H804 - H812. [Abstract] [Full Text] [PDF]
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 D. Rizzoni, S. Paiardi, L. Rodella, E. Porteri, C. De Ciuceis, R. Rezzani, G. E. M. Boari, F. Zani, M. Miclini, G. A. M. Tiberio, et al. Changes in Extracellular Matrix in Subcutaneous Small Resistance Arteries of Patients with Primary Aldosteronism J. Clin. Endocrinol. Metab., July 1, 2006; 91(7): 2638 - 2642. [Abstract] [Full Text] [PDF]
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A. M. Briones, F. E. Xavier, S. M. Arribas, M. C. Gonzalez, L. V. Rossoni, M. J. Alonso, and M. Salaices Alterations in structure and mechanics of resistance arteries from ouabain-induced hypertensive rats Am J Physiol Heart Circ Physiol, July 1, 2006; 291(1): H193 - H201. [Abstract] [Full Text] [PDF]
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P. Brassard, F. Amiri, and E. L. Schiffrin Combined Angiotensin II Type 1 and Type 2 Receptor Blockade on Vascular Remodeling and Matrix Metalloproteinases in Resistance Arteries Hypertension, September 1, 2005; 46(3): 598 - 606. [Abstract] [Full Text] [PDF]
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 S. Lehoux and A. Tedgui Making Up and Breaking Up: The Tortuous Ways of the Vascular Wall Arterioscler Thromb Vasc Biol, May 1, 2005; 25(5): 892 - 894. [Full Text] [PDF]
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E. L. Schiffrin and R. M. Touyz From bedside to bench to bedside: role of renin-angiotensin-aldosterone system in remodeling of resistance arteries in hypertension Am J Physiol Heart Circ Physiol, August 1, 2004; 287(2): H435 - H446. [Full Text] [PDF]
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D. L. Myers, K. J. Harmon, V. Lindner, and L. Liaw Alterations of Arterial Physiology in Osteopontin-Null Mice Arterioscler Thromb Vasc Biol, June 1, 2003; 23(6): 1021 - 1028. [Abstract] [Full Text] [PDF]
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A. R. Pries, B. Reglin, and T. W. Secomb Structural Adaptation of Vascular Networks: Role of the Pressure Response Hypertension, December 1, 2001; 38(6): 1476 - 1479. [Abstract] [Full Text] [PDF]
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H. D. Intengan and E. L. Schiffrin Vascular Remodeling in Hypertension: Roles of Apoptosis, Inflammation, and Fibrosis Hypertension, September 1, 2001; 38(3): 581 - 587. [Abstract] [Full Text] [PDF]
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 R. M. Touyz and E. L. Schiffrin Signal Transduction Mechanisms Mediating the Physiological and Pathophysiological Actions of Angiotensin II in Vascular Smooth Muscle Cells Pharmacol. Rev., December 1, 2000; 52(4): 639 - 672. [Abstract] [Full Text] [PDF]
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H. D. Intengan and E. L. Schiffrin Structure and Mechanical Properties of Resistance Arteries in Hypertension : Role of Adhesion Molecules and Extracellular Matrix Determinants Hypertension, September 1, 2000; 36(3): 312 - 318. [Abstract] [Full Text] [PDF]
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 Jeong Bae Park, H. D Intengan, and E. L Schiffrin Reduction of resistance artery stiffness by treatment with the AT1-receptor antagonist losartan in essential hypertension Journal of Renin-Angiotensin-Aldosterone System, March 1, 2000; 1(1): 40 - 45. [Abstract] [PDF]
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H. D. Intengan, G. Thibault, J.-S. Li, and E. L. Schiffrin Resistance Artery Mechanics, Structure, and Extracellular Components in Spontaneously Hypertensive Rats : Effects of Angiotensin Receptor Antagonism and Converting Enzyme Inhibition Circulation, November 30, 1999; 100(22): 2267 - 2275. [Abstract] [Full Text] [PDF]
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