From the Division of Nephrology, Department of Medicine, University of
California at Irvine.
Endothelium-derived NO plays a major role in regulation
of vascular tone, hence vascular resistance and arterial
blood pressure. NO is produced from the conversion of
L-arginine to L-citrulline by a family of
enzymes known as NOS. The available data on the
L-arginine/NO pathway in SHR are limited and apparently
contradictory. Both decreased6 7 8 9 10 and
increased11 12 13 14 15 L-arginine/NO pathway
activities have been reported by different investigators. The
present study was designed to explore NO production as well
as renal and vascular NOS expression in young SHR before and after the
onset of hypertension. The study revealed strong evidence for
upregulation of NO production together with increased iNOS and
eNOS protein expressions in prehypertensive and hypertensive SHR. These
findings exclude a depressed L-arginine/NO pathway as the
primary cause of hypertension in SHR. On the contrary, the study points
to the activation of this pathway in these animals.
Prehypertensive Group
Tissue Preparation
NOS Activity Assay
Western Blot Analysis
Measurements of Total Nitrate and Nitrite
Samples were injected into the purge vessel to react with the
VCl3/HCl reagent, which converted nitrate,
nitrite, and S-nitroso compounds to NO. The NO produced was
stripped from the reaction chamber (by purging with nitrogen and
vacuum) and detected by ozone-induced chemiluminescence in the
chemiluminescence detector. The signal generated (NO peak and peak
area) was recorded and processed by a Hewlett Packard model 3390
integrator. In a typical assay, 5 µL of the test sample was injected
into the purge vessel, and all samples were run in triplicate.
Standard curves were constructed using various concentrations of
NO3- (5 to 100 µmol/L),
relating the luminescence produced to the given
NO3- concentrations of the
standard solutions. The amount of
NO2-/NO3-
in the test sample was determined by interpolation of the result into
the standard curve.
Data Presentation and Analysis
Body weight in the 3-week-old prehypertensive SHR group was slightly
but significantly higher than the corresponding value observed in the
WKY group. No significant difference was found in either hematocrit,
plasma creatinine, or creatinine clearance
between the two 3-week-old groups.
Plasma and Urinary NOx
NOS Activity and eNOS and iNOS Proteins
The original group of SHR used here was studied between the ages
of 8 and 12 weeks, representing the developmental phase of
hypertension in this model. We elected to study the animals at the
early phase of evolution of hypertension to distinguish the primary
changes of NO metabolism from those caused by long-standing
progressive hypertension and the resultant vasculopathy. The 8-week-old
SHR showed a significant lower initial body weight and a significantly
slower rate of growth during the 4-week observation period compared
with their WKY counterparts. However, differences in body weight should
not affect the validity of the biochemical measurements
presented here. This is because efforts were made to normalize
the given parameters when possible. For instance, urinary
NOx was normalized against creatinine excretion,
creatinine clearance was corrected for body weight, and NOS
activity and protein mass data represent amounts present in
fixed amounts of total tissue protein.
The SHR showed a marked increase in urinary NOx excretion,
pointing to increased total body NO production during the early
phase of hypertension. In addition, NOS activity as well as eNOS and
iNOS proteins were significantly increased in the vascular tissue of
SHR. Likewise, both iNOS and eNOS protein contents of the kidney tissue
were markedly elevated in the 12-week-old SHR. These findings point to
the upregulation of NOS protein expression and increased NO
production in the early phase of the evolution of hypertension
in SHR. Accordingly, the onset of hypertension in SHR is not due to
depressed NO production or NOS deficiency.
In an attempt to determine the possible role of hypertension per
se in the upregulation of NOS expression, we studied a group of
prehypertensive SHR and their normotensive WKY counterparts. We were
surprised to find a marked increase in urinary NOx excretion together
with a significant increase in the aorta eNOS and kidney iNOS protein
abundance in prehypertensive 3-week-old SHR when compared with
age-matched WKY. The mechanism and biological significance of
upregulation of the L-arginine/NO system in prehypertensive
SHR is not certain. However, it may be due to the hyperdynamic state
preceding the onset of progressive hypertension in these animals.
It is of interest that upregulation of the
L-arginine/NO pathway in SHR involved both eNOS and iNOS.
While the vasoregulatory role of eNOS as the source of EDRF is well
understood, the role of low-level iNOS expression is less clear. It
should be noted, however, that contrary to the conventional view, iNOS
is constitutively expressed in several tissues, including kidney (thick
ascending limb of loop of Henle, glomeruli, and interlobular and
arcuate arterioles), heart, and arterial
wall.21 22 23 The constitutive expression of this
NOS isotype in the kidney and other tissues points to its homeostatic
role apart from that associated with its inducible immunologically
mediated activation.
It should be noted that increased NOS protein abundance and NO
production during the early phase of evolution of hypertension
in SHR do not necessarily denote their persistent elevation during the
advanced phase of the disease. On the contrary, with progressive
vasculopathy and endothelial dysfunction, NOS
expression and NO production may fall, leading to true NO
deficiency in animals with advanced hypertension. The resulting NO
deficiency can in turn contribute to the worsening of hypertension and
the associated progressive vasculopathy. In fact, Cuevas et
al6 have shown a dramatic decline in the
percentage of endothelial cells with detectable eNOS on
histochemical examination of thoracic aorta in aged SHR. In contrast,
age-matched normotensive WKY showed no discernible decline in
immunostainable eNOS of thoracic aorta
endothelial cells. Thus, the results of the present
study and those of other investigators showing increased
L-arginine/NO pathway activity in young spontaneously
hypertensive animals10 11 12 13 14 15 do not necessarily
contradict those of Cuevas et al in aged SHR.6
Instead, the data most likely represent different points in the
natural course of progressive hypertension and vasculopathy in this
model. Further studies are required to examine this possibility.
In conclusion, development of hypertension in young SHR is
preceded by and associated with enhanced total body NO
production and increased vascular and renal NOS protein
expressions. These findings tend to exclude an impaired
L-arginine/NO pathway as the primary cause of hypertension
in SHR.
Received December 8, 1997;
first decision January 6, 1998;
accepted January 13, 1998.
2.
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M, Cuevas B, Munoz-Willery I, Martinez-Coso F, Lamas S, Gimenez-Gallego
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7.
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8.
Malinsky T, Kapturczak M, Dayharsh J, Bohr D. Nitric
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9.
Crabos M, Coste P, Paccalin M, Tariosse L, Daret D,
Besse D, Bonoron-Adele S. Reduced basal NO-mediated dilation and
decreased NO-synthase expression in coronary vessels of
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10.
Sunano S, Li-Bo Z, Matsuda K, Sekiguchi F, Watanabe H,
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oxide tone in normotensive and genetically hypertensive rats. Eur
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enhanced in the vasculature and renal medulla of spontaneously
hypertensive rats but fails to control hypertension. J Am
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© 1998 American Heart Association, Inc.
Scientific Contributions
Upregulation of Renal and Vascular Nitric Oxide Synthase in Young Spontaneously Hypertensive Rats
Abstract
Top
Abstract
Introduction
Methods
Results
Discussion
References
Abstract—The available data on the
role of the L-arginine/nitric oxide (NO) pathway in the
genesis of hypertension in spontaneously hypertensive rats (SHR) are
limited and contradictory. In an attempt to address this issue, male
SHR were studied during the early phase of evolution of hypertension
(age 8 to 12 weeks) to distinguish the primary changes of NO
metabolism from those caused by advanced hypertension,
vasculopathy, and aging late in the course of the disease. A group of
age-matched male Wistar-Kyoto rats (WKY) served as controls. The SHR
exhibited a marked rise in arterial blood pressure and a
significant increase in urinary excretion and plasma concentration of
NO metabolites (nitrite/nitrate [NOx]). Likewise, the SHR showed a
significant elevation of thoracic aorta NO synthase (NOS) activity
coupled with significant increases of kidney, aorta, inducible NOS
(iNOS), and endothelial NOS (eNOS) proteins. In an
attempt to determine whether the enhanced L-arginine/NO
pathway is a consequence of hypertension, studies were repeated using
3-week-old animals before the onset of hypertension. The study revealed
significant increases in urinary NOx excretion as well as vascular eNOS
and renal iNOS proteins. In conclusion, the L-arginine/NO
pathway is upregulated in young SHR both before and after the onset of
hypertension. Thus, development of hypertension is not due to a primary
impairment of NO production in SHR. On the contrary, NO
production is increased in young SHR both before and after the
onset of hypertension.
Key Words: nitric oxide • nitric oxide synthase • endothelium-derived relaxing factor • kidney
Introduction
Top
Abstract
Introduction
Methods
Results
Discussion
References
Spontaneously
hypertensive rats originated from the mating of a normotensive pair of
WKY. These animals exhibit severe progressive hypertension that begins
at 
5 weeks of age and leads to severe vasculopathy. The course of
genetic hypertension in SHR bears a resemblance to that of essential
hypertension in humans. Thus, SHR have been widely used as a model to
study the mechanism, pathophysiology, and management of idiopathic
hypertension. These investigations have revealed several abnormalities
of vasoregulatory factors, including the renin-angiotensin
system, catecholamines, vasopressin, and vasoactive
intestinal peptide in SHR.1 2 3 4 5
Methods
Top
Abstract
Introduction
Methods
Results
Discussion
References
Animals
Eight-week-old male SHR and WKY were purchased from Harlan
Sprague-Dawley, Inc (Indianapolis, Ind). The animals were fed a
low-nitrate basic diet (Purina Mills) and water ad libitum. They were
housed in a climate-controlled, light-regulated space with 12-hour
light (>500 lux) and dark (<5 lux) cycles. Eight animals were
included in each group. Tail arterial blood pressure was
determined using a tail sphygmomanometer (Harvard
Apparatus) at baseline (8 weeks of age) and at weeks 10 and
12. At the conclusion of the study, animals were placed in
metabolic cages for 24-hour urine collection. The urine
samples were collected in sterilized containers that were chilled over
ice and stored at -70°C until assayed. The animals were then killed
by exsanguination using cardiac puncture between the hours of 9
AM and 11 AM, and blood, kidney, and thoracic
aortas were harvested immediately. The tissues were snap-frozen in
liquid nitrogen immediately and stored at -70°C until
processing.
In an attempt to discern the effect of hypertension per se on NO
metabolism, we studied a group of 3-week-old SHR during the
prehypertensive phase and compared the results with those obtained in
their WKY counterparts. These animals were purchased from Harlan
Sprague-Dawley, Inc. They were placed in metabolic cages
for timed urine collection after which they were killed by
exsanguination, and blood and tissues were harvested and processed as
described above.
Thoracic aorta and kidney were used for determination of NOS.
Rats were killed by cardiac puncture, and thoracic aorta and kidney
were immediately excised, cleaned with PBS, frozen in liquid nitrogen,
and stored at -70°C. Homogenates (25% wt/vol) were
prepared in 10 mmol/L HEPES buffer, pH 7.4, containing 320
mmol/L sucrose, 1 mmol/L EDTA, 1 mmol/L DTT, 10 µg/mL
leupeptin, and 2 µg/mL aprotinin at 0°C to 4°C with the aid of a
tissue grinder fitted with a motor-driven ground glass pestle.
Homogenates were centrifuged at 12 000g
for 5 minutes at 4°C to remove tissue debris without precipitation of
plasma membrane fragments.10 11 The supernatant
was used for determination of NOS activity and protein mass. Protein
concentration was determined with a Bio-Rad kit.
NOS activity was measured as previously
described.16 In brief, enzyme reactions were
conducted at 37°C for 30 minutes in 40 µL of the supernatant and
100 µL of 40 mmol/L potassium phosphate buffer, pH 7, containing
4.8 mmol/L DL-valine, 1 mmol/L NADPH, 1
mmol/L MgCl2, 2 mmol/L
CaCl2, 20 µmol/L L-arginine, 1
µg/mL calmodulin, and 1.25 µL/mL
L-[3H]arginine (59 Ci per
mmol/L, Amersham Life Science Inc). On each occasion, parallel
measurements were obtained in the presence and absence of 1 mmol/L
NG-methyl-L-arginine. The
reactions were terminated by 0.86 mL ice-cold stop buffer containing
0.2 mmol/L EDTA. Dowex 50W-X8 resin (250 mg,
Na+ form) was added to a 0.25-mL aliquot of the
reaction mixture and shaken for at least 5 minutes to remove the
remaining L-arginine. The Na+ form of
Dowex 50W was prepared by washing the H+ form of
the resin (100 to 200 mesh, Bio-Rad) with 1 mol/L NaOH four times and
then washing with H2O until the pH fell below
7.5. The above mixture was then centrifuged, and a 100-µL
aliquot of the supernatant containing L-citrulline was
mixed with 10 mL of scintillation cocktail in a 20-mL scintillation
vial and counted by a Beckman LS-9000 counter. Net radioactivity was
determined by substrating the counts per minute observed in the
presence of
NG-methyl-L-arginine from that
observed in the absence of
NG-methyl-L-arginine. NOS
activity was determined from the production of
[3H]citrulline per minute per milligram of
protein.
These measurements were carried out to determine the eNOS and
iNOS protein mass as previously described.17 18
Anti-eNOS monoclonal antibody, peroxidase-conjugated goat anti-mouse
IgG antibody, anti-Mac NOS-I, human
endothelial–positive control, and mouse
macrophage–positive control were supplied by Transduction
Laboratories. Briefly, aorta and kidney tissue preparations (50 µg of
protein for the aorta and 100 µg for the kidney) were
size-fractionated on 4% to 12% Tris-Glycine gel (Novex) at 120 V for
3 hours. In preliminary experiments, we found that the given protein
concentrations were within the linear range of detection for our
Western blot technique. After electrophoresis, proteins were
transferred onto Hybond-ECL membrane (Amersham Life Science Inc) at 400
mA for 120 minutes using the Novex transfer system. The membrane was
prehybridized in 10 mL of buffer A (10 mmol/L Tris hydrochloride,
pH 7.5, 100 mmol/L NaCl, 0.1% Tween 20, and 10% nonfat milk
powder) for 1 hour and then hybridized for an additional 1-hour period
in the same buffer containing 10 µL of the given anti-NOS monoclonal
antibody (1:1000). The membrane was then washed for 30 minutes in a
shaking bath, with the wash buffer (buffer A without nonfat milk)
changed every 5 minutes before 1 hour of incubation in buffer A plus
goat anti-mouse IgG–horseradish peroxidase at the final titer of
1:1000. Experiments were carried out at room temperature. The washes
were repeated before the membrane was developed with a light-emitting
nonradioactive method using ECL reagent (Amersham Inc). The membrane
was then subjected to autoluminography for 1 to 5 minutes. The
autoluminographs were scanned with a laser densitometer (model PD1211,
Molecular Dynamics) to determine the relative optical densities of the
bands. In all instances, the membranes were stained with Ponceau stain
before prehybridization. This step verified the uniformity of protein
load and transfer efficiency across the test samples.
The concentration of total nitrate and nitrite in the test
samples was determined by a modification of the procedure described by
Braman and Hendrix19 using the purge system of a
Sievers Instruments model 270B nitric oxide analyzer (NOA 228,
Sievers Instruments Inc). Briefly, plasma samples were first diluted
and deproteinized using chilled 100% ethanol (sample/ethanol, 1:2
[vol/vol]), and urine samples were diluted 10 times in distilled
water before analysis.20 A saturated
solution of VCl3 in 1 mol/L HCl was prepared and
filtered before use. This reagent (5 mL) was added to the purge vessel
and purged with nitrogen gas for 5 to 10 minutes before use. The purge
vessel was equipped with a cold-water condenser and a water jacket to
permit heating of the reagent to 95°C with a circulating water bath.
The hydrochloric acid vapors were removed by a gas bubbler containing
15 mL of 1 mol/L NaOH. The gas flow rate into the chemiluminescence
detector was controlled using a needle valve adjusted to yield a cell
pressure of 7 mm Hg. The flow rate of nitrogen into the purge
vessel was adjusted to prevent vacuum distillation of the reagent.
Data are given as mean±SEM. Multiple-measure ANOVA, Student's
t test, and regression analysis were used in the
statistical evaluation of the data as appropriate. Values of
P
.05 were considered significant.
Results
Top
Abstract
Introduction
Methods
Results
Discussion
References
General Data
Data are shown in Tables 1
and 2 and Figure 1. Initial body weight and
creatinine clearance in the 8-week-old SHR were
significantly lower than the corresponding values found in the WKY
animals. Although body weight and creatinine clearance
increased in both groups during the observation period, they remained
significantly lower in the SHR than in the WKY group. Initial
arterial blood pressure obtained at 8 weeks of age in the
SHR was significantly higher than that found in the WKY group. During
the observation period, blood pressure rose significantly above the
initial value in the SHR but remained practically unchanged in the WKY
group. No significant difference was found in hematocrit level between
the two groups.
View this table:
[in a new window]
Table 1. Initial (Obtained at 8 Weeks of Age) and Final
(Obtained at 12 Weeks of Age) Measurements of Body Weight, Hematocrit,
Plasma Creatinine, and Creatinine Clearance in
SHR and WKY
View this table:
[in a new window]
Table 2. Body Weight, Hematocrit, Plasma
Creatinine, and Creatinine Clearance in
Prehypertensive 3-Week-Old SHR and Age-Matched WKY
View larger version (34K):
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Figure 1. Tail systolic blood pressure obtained at
ages 8, 10, and 12 weeks in SHR and WKY. n=6 in each group.
*P<0.01 vs WKY group.
Data are shown in Figure 2. Urinary
excretion of NOx in both prehypertensive (3-week-old) and hypertensive
(12-week-old) SHR was significantly greater than in the corresponding
WKY groups. Likewise, plasma NOx concentration was significantly higher
in the SHR when compared with the corresponding value found in the WKY
group.
View larger version (25K):
[in a new window]
Figure 2. Plasma concentration (top) and urinary excretion of
stable nitric oxide metabolites (NOx; bottom) in SHR and WKY. n=6 in
each group. *P<0.01.
Data are shown in Figures 3 through 11.
At 12 weeks of age, thoracic aorta NOS activity was significantly
greater in the SHR than that found in the WKY group. This was
accompanied by a significant increase in the thoracic aorta iNOS and
eNOS proteins in the 12-week-old SHR. In addition, renal tissue iNOS
and eNOS protein abundance was markedly increased in these animals
compared with that in the WKY group. Interestingly, a marked increase
in kidney iNOS protein abundance as well as thoracic aorta eNOS protein
abundance was observed in 3-week-old prehypertensive SHR compared with
the corresponding values found in the age-matched WKY animals. However,
kidney tissue eNOS and aorta iNOS, which were markedly elevated in the
12-week-old SHR, were not yet increased in the prehypertensive
3-week-old SHR.
View larger version (13K):
[in a new window]
Figure 3. Aorta NOS activity in the SHR and WKY groups. n=6
in each group. *P<0.01.
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[in a new window]
Figure 4. A, Representative Western blot of
aorta eNOS protein in three 12-week-old SHR and three WKY. B, Group
data illustrating the optical densities of eNOS protein bands in the
study groups. n=6 in each group. *P<0.01.
View larger version (19K):
[in a new window]
Figure 5. A, Representative Western blot of
aorta iNOS in three 12-week-old SHR and three WKY. B, Group data
demonstrating the optical densities of aorta iNOS protein bands in the
study groups. n=6 in each group. *P<0.01.
View larger version (22K):
[in a new window]
Figure 6. A, Representative Western blot of
kidney eNOS in three 12-week-old SHR and three WKY. B, Group data
illustrating relative optical densities of kidney eNOS bands in the
study groups. n=6 in each group. *P<0.01.
View larger version (19K):
[in a new window]
Figure 7. A, Representative Western blot of
kidney iNOS in three 12-week-old SHR and three WKY. B, Group data
depicting relative optical densities of the kidney iNOS protein bands
in the study groups. n=6 in each group. *P<0.01.
View larger version (27K):
[in a new window]
Figure 8. A, Representative Western blot of
aorta eNOS protein in three prehypertensive 3-week-old SHR and three
WKY. B, Group data illustrating the optical densities of eNOS protein
bands in the study groups. n=6 in each group.
*P<0.05.
View larger version (34K):
[in a new window]
Figure 9. A, Representative Western blot of
aorta iNOS in three prehypertensive 3-week-old SHR and three WKY. B,
Group data demonstrating the optical densities of aorta iNOS protein
bands in the study groups. n=6 in each group.
View larger version (31K):
[in a new window]
Figure 10. A, Representative Western blot of
kidney eNOS in three prehypertensive 3-week-old SHR and three WKY. B,
Group data illustrating relative optical densities of kidney eNOS bands
in the study groups. n=6 in each group.
View larger version (25K):
[in a new window]
Figure 11. A, Representative Western blot of
kidney iNOS in three prehypertensive 3-week-old SHR and three WKY. B,
Group data depicting relative optical densities of the kidney iNOS
protein bands in the study groups. n=6 in each group.
*P<0.05.
Discussion
Top
Abstract
Introduction
Methods
Results
Discussion
References
Data on the status of the L-arginine/NO pathway
in SHR are contradictory. Although several studies have found evidence
for depressed NO production, others have suggested the
opposite. For instance, Cuevas et al6 have
recently demonstrated that the percentage of
endothelial cells with immunostainable eNOS
is greatly reduced in the thoracic aorta of aged SHR but not in
normotensive WKY animals. In addition, Dubois7
has recently shown that NO production and
L-citrulline release in response to stimulation with 5%
fetal calf serum, endotoxin, and interleukin-1ß is reduced in
cultured vascular smooth muscle cells obtained from SHR when compared
with cells derived from normotensive WKY animals. On the basis of these
findings, the author concluded that vascular smooth muscle iNOS
activity is depressed in SHR. Likewise, Malinsky et
al8 have demonstrated depressed NO
production in response to bradykinin stimulation in cultured
endothelial cells from SHR when compared with cells
obtained from normotensive WKY animals. Furthermore, Crabos and
coworkers9 have recently shown that compared with
WKY, 20-week-old SHR exhibit decreased vasodilatory response to
bradykinin, reduced sensitivity to NOS inhibition, and diminished
immunohistochemically detectable eNOS in the coronary arteries.
In another study, Sunano and associates10 showed
a significant impairment of vasodilatory response to
2-adrenoreceptor agonist and,
to a lesser extent, acetylcholine in precontracted aorta rings from SHR
compared with those of WKY. They further demonstrated that these
vasodilatory responses were completely inhibited by NOS
inhibitor, pointing to the role of NO in this process. On
the basis of these observations, the authors concluded that the
impaired vasodilatory response to
2-adrenoreceptor agonist and
acetylcholine is due to depressed NO production in SHR. They
further speculated that impaired 2
agonist-mediated NO production may in part contribute to
hypertension in SHR.10 In contrast, Akiba et
al11 have recently produced indirect evidence for
increased NO production in young (6-week-old) and adult
(20-week-old) SHR compared with WKY of the same age. This conclusion
was based on the greater hypertensive response to NOS blockade in SHR
than in WKY.11 Similarly, Gil-Longo and
coworkers12 found a significantly greater
hypertensive response to NOS blockade, suggesting increased resting NO
production in SHR compared with WKY. However, the magnitude of
contractile response to NOS inhibitor and methylene blue
(an NO quencher) was significantly lower in submaximally contracted
(25 mmol/L KCl) aortic rings from SHR than from WKY. On the basis
of these observations, they suggested that hypertension enhances NO
tone in vivo but impairs vascular NO production in
vitro.12 Further support for the
hypertension-induced increased NO production in SHR comes from
recent studies of Tomita et al,13 who showed a
direct correlation between blood pressure and acetylcholine-induced
vasorelaxation in aortic rings of 9-week-old SHR, WKY, and F1-hybrid
rats. They further showed that correction of hypertension with
antihypertensive therapy for 5 weeks reverses the exaggerated
acetylcholine-mediated vasorelaxation of the aortic rings in SHR, hence
substantiating the role of hypertension per se.13
These observations are further supported by recent studies of Hayakawa
et al,14 who have shown increased NOS activity in
the aorta and renal medulla of 16-week-old SHR compared with
normotensive WKY. In addition, Wu and
associates15 have found higher plasma nitrite and
tumor necrosis factor- concentrations and greater cGMP
production and iNOS expression by aorta smooth muscle in SHR
than in WKY at baseline and after lipopolysaccharide
stimulation. This was associated with a greater hypotensive response to
lipopolysaccharide in SHR as opposed to WKY. They concluded
that NO production is increased in SHR and attributed this
phenomenon to basal expression of
iNOS.15
Selected Abbreviations and Acronyms
EDRF
=
endothelium-derived relaxing factor
eNOS
=
endothelial nitric oxide synthase
iNOS
=
inducible nitric oxide synthase
NOS
=
nitric oxide synthase
NOx
=
nitrite/nitrate
SHR
=
spontaneously hypertensive rat(s)
WKY
=
Wistar-Kyoto rat(s)
Footnotes
Reprint requests to N.D. Vaziri, MD, Division of Nephrology and Hypertension, Department of Medicine, UCI Medical Center, 101 The City Dr, Orange, CA 92868.
References
Top
Abstract
Introduction
Methods
Results
Discussion
References
1.
Avidor R, Eilam R, Malach R, Gozes I. VIP-mRNA is
increased in hypertensive rats. Brain Res. 1989;503:304–307.[Medline]
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