(Hypertension. 2001;37:1164.)
© 2001 American Heart Association, Inc.
Scientific Contributions |
Decreased Renal Expression of Nitric Oxide Synthase Isoforms in Adrenocorticotropin-Induced and Corticosterone-Induced Hypertension
From the Department of Physiology and Institute for Biomedical Research (Y.L., D.J.A., B.J.M.), and Department of Pathology (F.Y), Basic & Clinical Genomics Laboratory, Department of Medicine (C.W., M.L., M.W.), St George Hospital, The University of Sydney; and The John Curtain School of Medical Research (J.A.W.), Australian National University, Canberra (Australia).
Correspondence to Judith A. Whitworth, The John Curtain School of Medical Research, Australian National University, PO Box 334, Canberra ACT 2601, Australia. E-mail Director{at}JCSMR.anu.edu.au
 |
Abstract |
|---|
 Top Abstract IntroductionMethodsResultsDiscussionReferences |
|---|
Abstract—Administration of adrenocorticotropic hormone (ACTH) leads to the development of hypertension. Because glucocorticoids can affect the nitric oxide system at several sites, the present study tested the hypothesis that nitric oxide synthase (NOS) expression may be altered in ACTH-induced and corticosterone-induced hypertension in the rat. This was addressed by measuring Nos1, Nos2, and Nos3 mRNA in the kidney, adrenal gland, heart, and hypothalamus of 16 ACTH-treated and 16 vehicle-treated rats as well as in 10 corticosterone-treated and 10 control rats. In addition, in situ hybridization and immunohistochemistry were used to confirm changes by detection of Nos in RNA and NOS protein in tissues. Systolic blood pressure of ACTH and corticosterone rats was elevated (165±6 and 162±11 mm Hg; P<0.001 versus control). Each Nos isoform mRNA was measured by reverse transcriptase-polymerase chain reaction technique. In ACTH rats, mRNA for Nos2 was reduced in renal cortex by 58±5% and in medulla by 68±7%; for Nos3, mRNA reductions of 59±6% and 51±11% were seen (P<0.001 after Hochberg correction for multiple comparisons). In corticosterone rats, Nos2 mRNA decreased in cortex by 68±5% and in medulla by 62±6%; Nos3 mRNA by 50±8% in cortex, and Nos1 by 29±7% in medulla (all P<0.001 after Hochberg correction). Reductions seen in kidney were supported by in situ hybridization and immunohistochemistry. Apart from a 62±2% decrease in Nos2 mRNA in adrenal of ACTH rats (corrected P<0.05), no significant changes were seen in the other nonrenal tissues for any isoform. In conclusion, we have shown for the first time that the physiological components of glucocorticoid action (ACTH and corticosterone) when given chronically in vivo reduce Nos2 and Nos3 expression in the kidney. Such changes are consistent with a role in hypertension for ACTH and corticosterone.
Key Words: immunohistochemistry • hybridization • RNA • nitric oxide • isoenzymes • reverse transcriptase–polymerase chain reaction
|
Introduction |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
Administration of adrenocorticotropin (ACTH) produces hypertension in humans, rats, dogs, and sheep, and excess endogenous secretion is associated with Cushing’s syndrome.1 The elevation in blood pressure (BP) is explicable by the action of cortisol in humans2 and corticosterone in the rat,3 but the mechanism by which these steroids raise BP is still not well understood. Studies of ACTH-induced and corticosterone-induced hypertension in the rat and cortisol-induced hypertension in humans suggest a role for the nitric oxide (NO) system in these forms of hypertension.3 4 5 Given that glucocorticoids are known to have several potential sites of action in the NO system, including an inhibitory effect on transmembrane L-arginine transport6 and suppression of nitric oxide synthase (NOS)27 as well as tetrahydrobiopterin synthesis,6 we wanted to define whether elements of the NO system are altered in ACTH-induced hypertension. Contrary to early views, reflected in their nomenclature, each NOS has varying degrees of constitutive and inducible capabilities.8 9 The aim of the present study was to examine NOS expression in ACTH, corticosterone, and vehicle-treated rats. Because dexamethasone can reduce human NOS3 promoter activity and mRNA stability10 and NOS2 control is at the level of transcription and protein stability,11 we looked for changes in Nos mRNA levels, and alterations were verified by examination of NOS protein changes in tissue sections.
|
Methods |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
Rats
Male 8-week-old Sprague-Dawley rats (250 to 280 g) from Animal Resources Center, Perth, Western Australia, were housed (4 rats per plastic cage) at 21°C to 23°C in the St George Animal House, which has separate rooms for surgery, BP monitoring, and metabolic studies. Rats were fed a commercial diet (Gordon’s Specialty Stock Feeds, Yanderra, NSW, Australia), and given free access to tap water. All procedures were ethically approved.
Determination of
Physiological Parameters
Every other day, body weight, 24-hour food and water
intake, urine volume, and excreted Na+ were
measured in separate 18x23x43-cm wire metabolic cages.
Systolic BP was recorded on alternating days by tail cuff
(Narco Biosystems, Inc). At least 5 consecutive cycles of
inflation/deflation were performed on each rat while it was conscious,
and the mean of the last 3 recordings, which showed no more
than a 10-mm Hg difference, was taken to be systolic
BP.
ACTH and Corticosterone Treatment
Protocols
Six days of control measurements were followed by 10
further days of measurements, during which ACTH or vehicle (0.9% NaCl)
was administered. Sixteen rats were injected (at 10
AM and 6
PM) with 0.25 mL/kg (0.5 mg
· kg-1 ·
d-1) SC synthetic ACTH (Synacthen Depot,
Novartis) BID. Concurrently, another 16 rats received 0.25 mL/kg
SC of vehicle BID. At the end of the experiment, rats were euthanatized
by use of pentobarbital (60 mg/kg IP). The corticosterone protocol was
similar, except that 10 rats were injected subcutaneously twice daily
with corticosterone (Sigma) 120 µmol ·
kg-1 · d-1 in
ethanol and 10 were given ethanol vehicle.
Biochemical Measurements
Blood samples of 6 to 8 mL were taken from the
cannulated carotid artery under anesthesia and stored at
–20°C. Urine samples were centrifuged at 3500 rpm for 15
minutes, aliquots were diluted 1:5 with distilled water, and
concentrations of Na+ and
K+ were measured with a I.L 643 Digital
Flame Photometer (Instrumentation Laboratory Inc). Corticosterone was
measured by radioimmunoassay (Coat-a-Count rat corticosterone kit;
Diagnostic Products Corp): assay sensitivity was 16
pmol/mL, and interassay and intra-assay coefficients of variation were
4.8% to 5.8% and 4.0% to 4.3%, respectively, at mean values of 1.2
nmol/mL for each.
Tissue Preparation and RNA Extraction
Tissues were excised and rinsed in PBS. Cortex and
medulla of the left kidney were dissected out, frozen in liquid
nitrogen, and stored at -80°C. The right kidney was fixed in 4%
paraformaldehyde/10% phosphate buffer, pH 7.4, for
immunohistochemical studies. Extraction of total RNA from left kidney
was done with RNazol B solution (Bresatec) in a Polytron
homogenizer. RNA samples were stored in
diethylpyrocarbonate-treated water with 2 µg of tRNA at -80°C for
<4 months. Integrity of RNA was assessed by gel electrophoresis. RNA
concentrations were estimated from absorption at 260
nm.
Nos
mRNA Measurements
Nos mRNA
isoforms were semiquantified by a reverse-transcriptase–polymerase
chain reaction (RT-PCR) method. For the RT step, a 3-µL aliquot (3
µg) of total RNA was dissolved in 20 µL of reaction mixture that
contained 1 mmol/L dNTP, 1 U RNasin (Promega), 100 pmol/L random
hexamers (Promega), reaction buffer (final concentration contained
50 mmol/L KCl, 20 mmol/L Tris-HCl [pH 8.4], 2.5 mmol/L
MgCl2, and 10 µg/µL nuclease-free BSA), and
200 U of murine leukemia virus reverse-transcriptase (Gibco BRL) and
kept at 42°C for 60 minutes. The enzyme was inactivated
by increasing the temperature to 96°C for 5 minutes. Samples then
were cooled to 4°C. For the PCR step, 3 µL of the resulting RT
mixture was transferred into 30 µL of reaction buffer (see above)
that contained 50 pmol/L specific primer and 5 U of
Taq polymerase (Gibco BRL). A
separate PCR mixture was made for each
Nos isoform mRNA and ß-actin
mRNA internal control, to give 4 tubes for each sample. To reduce
cross-hybridization and enhance specificity, primers for
Nos1,
Nos2, and
Nos3 cDNAs were chosen for
minimum interisoform homology. Primer and PCR product sizes are
shown in the
Table.
PCR involved 34 cycles of 95°C, 60°C, and 72°C for 1 minute each
in a Perkin-Elmer/Cetus model 480 thermal cycler. ß-actin PCR
comprised 24 cycles of 95°C, 62°C, and 72°C for 1 minute
each.
|
PCR product size was seen by electrophoresis on a 3%
agarose gel of 3 µL of each of the 4 PCR product mixtures
combined. Specificity of RT-PCR products was confirmed by Southern
blot transfer onto Hybond-N+ nylon membrane
(Amersham) and probing with oligonucleotide
(Table)
end-labeled with [
-32P]ATP (Amersham)
by use of T4 polynucleotide kinase (New England BioLabs).
Hybridization was performed in 6xSSC, 5xDenhardt’s, and 0.1% SDS at
42°C. After high-stringency washing of the product,
autoradiography was performed at -80°C
overnight.
Quantity of PCR product was assessed by dot-blot hybridization.12 Briefly, 5 µL of each PCR product mixture was denatured at 22°C for 30 minutes with 500 µL of 0.4 mol/L NaOH and 10 mmol/L EDTA to give 2-fold dilutions. Samples were then transferred onto Hybond-N+ membranes by use of a dot-blot apparatus (BioRad). DNA then was immobilized with GS Gene Linker (BioRad) and hybridized at 42°C for 4 hours with internal oligonucleotide probes (see above). After a high-stringency wash was completed, membranes were exposed to Kodak X-ray film at 22°C for 4 to 8 hours. Optical density of spots on autoradiograms was measured with a Molecular Dynamics personal densitometer (Qune Corp). For each tissue sample with each probe, 3 measurements of signal intensity at different dilutions were obtained. Nos mRNA concentration was expressed relative to ß-actin signal. Within-assay and between-assay variation was 5.9% and 8.4%, respectively. For each experiment, a set of RNA preparations for each tissue underwent RT-PCR through to quantification together, to avoid time-dependent degradation of RNA or cDNA and to reduce run-to-run differences in amplification efficiency.
In Situ Hybridization Histochemistry
Nos2 and
Nos3 PCR products were
subcloned into pGEM-Teasy (Promega). Antisense and sense
riboprobes that incorporated digoxigenin-11-UTP (Boehringer
Mannheim) were generated with T7 and SP6 polymerases, respectively.
Tissue was collected into 10% neutral buffered formalin, and sections
were applied to slides prepared under RNase-free conditions. After
dewaxing and rehydration, sections were treated with proteinase K,
fixed in 4% paraformaldehyde, and acetylated
with 0.1 mol/L triethanolamine HCl and 0.25% acetic anhydride (pH
8.0). Prehybridization was performed in a 42°C humidified chamber
with buffers supplied in the Boehringer in situ hybridization
kit. Slides were drained, incubated overnight at 42°C in
hybridization buffer with 10 to 20 ng/µL of riboprobe, and washed to
remove unbound probe as described in the kit instructions. After being
blocked, sections were incubated for 4 hours at 22°C with 1:500
antidigoxigenin antiserum conjugated with alkaline phosphatase. RNA-RNA
hybrids were then detected colorimetrically with nitro
blue tetrazolium. Slides were counterstained with hematoxylin
and dehydrated. Coverslips were applied, and slides were examined and
photographed with a light photomicroscope.
Immunohistochemistry
Longitudinal (coronal) slices of 3 to 4 mm of
fixed right kidney were embedded, and 5-µm sections were mounted on
silane-coated slides, deparaffinized in xylene, and rehydrated through
graded alcohols. Next, antigen retrieval solution (Dako Corp) was
applied and endogenous peroxide activity blocked with 3%
H2O2 for 10 minutes.
Nonspecific staining was blocked with 2% skim milk powder in 50
mmol/L Tris-buffered saline. Anti-mouse macrophage-derived
NOS2 and anti-mouse NOS3 monoclonal antibodies (Transduction
Laboratories), each at 1:200, were applied, and sections were incubated
in a humidity chamber for 1 hour at 22°C. An LSAB 2 kit (Dako) was
then used to detect immunoreactivity. Sections were incubated
sequentially with biotinylated-link antibody, peroxidase-labeled
streptavidin, and DAB-substrated chromogen and counterstained or not
with hematoxylin. Positive staining gave a brown product. Negative
control omitted antibody.
Statistical Analysis
A Microsoft Excel Statistical Analysis
Package was used for t tests.
Hochberg correction was applied to adjust for multiple
comparisons.13
|
Results |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
BP and Body Weight
Systolic BP of the 16 ACTH-treated rats was (mean±SE) 165±6 mm Hg and of the 16 control rats was 127±2 mm Hg (P<0.001). For the 10 corticosterone-treated (corticosterone) and 10 control rats, BPs were 162±11 and 111±6 mm Hg (P<0.001). ACTH reduced body weight (272±3 versus 214±4 g; P<0.001), as did corticosterone (261±11 versus 226±20 g; P<0.001). ACTH increased water intake (32±1 versus 71±4 mL/d; P<0.001), but corticosterone did not (31±1 versus 35±3 mL/d). Both increased urine volume: 6±1 versus 41±2 mL/d (P<0.001) and 5±1 versus 13±1 (P<0.01), respectively. Food intake was 28±1 g/d before ACTH treatment and >24±1 g/d during treatment. For corticosterone, food intake was 31±1 g/d before and >24±1 during treatment. Urinary Na+ (mmol/d) was increased on treatment days 1 (control versus ACTH, 0.95±0.04 versus 1.55±0.15; P<0.01), 5 (0.95±0.04 versus 1.44±0.09, P<0.01), and 7 (0.95±0.04 versus 1.32±0.10; P<0.01), with no change in urinary K+ (2.30±0.08 versus 2.16±0.30 mmol/d on day 7). Na+ and K+ were not measured in corticosterone rats. Serum corticosterone at euthanatization was 4.0±0.3 in ACTH versus 1.1±0.05 nmol/mL in control rats (P<0.001) and 1.5±0.06 in corticosterone versus 1.0±0.07 nmol/mL in control rats (P<0.01).
Confirmation of Identity of PCR
Products
RT-PCR products of the expected sizes were found
for each of the 3 Nos isoform
mRNAs in all tissues examined. A typical ethidium bromide–stained gel
of RT-PCR products is shown in
Figure 1. Southern blotting detected a signal of expected
size in each case (not shown).
|
Nos
Isoform mRNA Concentrations in ACTH and Control Rats
In kidney, Nos2
and Nos3 mRNA were reduced by
58±5% and 59±6%, respectively, in cortex and 68±7% and 51±11%
in medulla, but no change occurred in
Nos1 mRNA
(Figure 2). Decreases remained significant after correction
for multiple comparisons
(P<0.01).
Nos2 mRNA in adrenal
(3.08±0.49) was higher than kidney and was reduced by 62±2% with
ACTH to 1.16±0.07 (P=0.005),
which remained significant
(P<0.05) after Hochberg
correction. A 46% decrease in
Nos1 mRNA was seen in
hypothalamus (0.91±0.09 versus 1.68±0.23;
P=0.03), but significance was
lost after Hochberg correction. No other changes were seen.
|
Nos
Isoform mRNA Concentrations in Corticosterone and Control Rats
Corticosterone reduced
Nos2 mRNA in renal cortex by
68±5% and in medulla by 62±6%
(Figure 3). Nos3 mRNA
was decreased by 50±8% and 23±7%, respectively.
Nos1 mRNA declined 29±7% in
medulla. Significance remained after Hochberg correction, except for
Nos3 in
medulla.
|
Tissue Localization
An in situ hybridization signal for
Nos2 mRNA was detected in
kidney in distal convoluted tubule and collecting duct and was weaker
for ACTH than control rats
(Figure 4). Sense negative control gave no signal, which
supported specificity. A similar pattern was seen with
immunohistochemistry
(Figure 5): in control rats, medulla showed strongest
immunoreactivity, with brown cytoplasmic staining seen in late distal
convoluted tubule and collecting duct. In ACTH rats,
immunostaining was markedly weaker. In contrast, NOS2
immunostaining was not detected in renal
arterial vasculature, glomerular capillaries,
or proximal tubule of control or ACTH rats, consistent with an
absence of basal expression in these tissues. No staining was seen in
negative control in which preimmune serum was substituted for NOS2
antibody (result not shown). Results for corticosterone rats were
similar
(Figure 6). In the case of NOS3, signal seen in vascular
structures of kidney was decreased by ACTH and corticosterone
(Figure 7).
|
|
|
|
|
Discussion |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
We found that the rise in BP and metabolic changes in response to ACTH14 and corticosterone are accompanied by reductions in Nos2 and Nos3 isoform mRNAs and encoded proteins in kidney. A decrease in Nos1 mRNA was seen in renal medulla in response to corticosterone. Relative concentrations we saw were similar to those reported by others.15 Not only Nos3, but also Nos2 is expressed constitutively in the kidney,16 17 18 and the decrease in each of these mRNAs we saw by RT-PCR and by in situ hybridization was confirmed by immunohistochemistry of NOS2 and NOS3 proteins. Our findings thus indicate an action of ACTH and corticosterone to suppress Nos mRNAs. Moreover, the localization that we saw was similar to that which others have found in unstimulated rat kidney. NOS2 is found primarily in intercalated cells of the inner medullary collecting duct and distal convoluted tubule.16 18 19 Moreover, the inner medullary collecting duct is the site of highest NOS activity in the kidney and contains mRNA for each isoform.20 Although others have found evidence for low basal expression of NOS2 in the afferent arteriole and S3 segment of proximal convoluted tubule,19 this has not been observed consistently and was not seen by us. In the case of NOS3 protein and Nos3 mRNA, localization has been noted by others in the vasculature,19 21 with Nos1 and Nos3 mRNAs being detected in microdissected glomeruli and vasa recta.20
The decreases in NOS isoforms seen in kidney and vasculature could contribute to the hypertension produced by ACTH and corticosterone in the rat, because high basal NO release seen in kidney contributes substantially to acute and long-term control of Na+ and water homeostasis and BP.22 When NO synthesis is inhibited, the long-term pressure-natriuresis relationship is shifted to the right along the BP axis.23 In addition to acting as a vasodilator, NO inhibits both Na+ and water reabsorption by the collecting ducts,24 25 and selective blockade of renal NOS2 results in a 14-mm Hg rise in BP in rats. This rise can be prevented by administration of oral L-arginine.26 Moreover, NOS2 has been implicated in some other models of hypertension in rats.27 28 29 30 In ACTH-induced hypertension, changes in cardiac output and total peripheral resistance are not critical for the rise in BP, whereas prevention of the rise in renal vascular resistance prevented hypertension,31 consistent with a primary role for reduction in a renal vasodilator. The decreased NOS3 we saw in the renal vasculature might thus be of pivotal significance in the ACTH model of hypertension in the rat.
In conclusion, the present study suggests that part of the mechanism of ACTH-induced and corticosterone-induced hypertension in the rat could involve suppression of NOS2 and NOS3 expression in kidney. Because the major ACTH-stimulated adrenal corticosteroid in man, cortisol, might also be involved in essential hypertension,32 decreases in NOS in the origin of the latter merits further investigation.
|
Acknowledgments |
|---|
The present study was supported by grant 970931 from the National Health Medical Research Council of Australia. ACTH was a gift from Novartis.
|
Footnotes |
|---|
Dr Li is currently with Victor Chang Institute for Cardiac Research, St Vincent’s Hospital, Sydney.
Received August 8, 2000; first decision August 28, 2000; accepted September 29, 2000.
|
References |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
1. Whitworth JA. Cushing’s syndrome and hypertension. In: Swales JD, ed. Textbook of Hypertension. Oxford, UK: Oxford University Press; 1994:893–903.
2. Whitworth JA, Saines D, Scoggins BA. Blood pressure and metabolic effects of cortisol and deoxycorticosterone in man. Clin Exp Hypertens. 1984;6:795–809.
3. Mangos GJ, Turner SW, Fraser TB, Whitworth JA. The role of corticosterone in corticotrophin (ACTH)-induced hypertension in the rat. J Hypertens. 2000;18:1849–1855.[Medline] [Order article via Infotrieve]
4.
Turner SW, Wen C, Li
M, Whitworth JA. L-arginine prevents corticotropin-induced
increases in blood pressure in the rat.
Hypertension. 1996;27:184–189.
5. Kelly JJ, Tam SH, Williamson PM, Lawson J, Whitworth JA. The nitric oxide system and cortisol-induced hypertension in humans. Clin Exp Pharmacol Physiol. 1998;25:945–946.[Medline] [Order article via Infotrieve]
6.
Simmons WW,
Ungureanu LD, Smith GK, Smith TW, Kelly RA. Glucocorticoids regulate
inducible nitric oxide synthase by inhibiting tetrahydrobiopterin
synthesis and L-arginine transport.
J Biol Chem. 1996;271:23928–23937.
7.
Radomski MW, Palmer
RM, Moncada S. Glucocorticoids inhibit the expression of an inducible,
but not the constitutive, nitric oxide synthase in vascular
endothelial cells. Proc
Natl Acad Sci
U S A. 1990;87:10043–10047.
8. Hecker M, Cattaruzza M, Wagner AH. Regulation of inducible nitric oxide synthase gene expression in vascular smooth muscle cells. Gen Pharmacol. 1998;32:9–16. Review.
9.
Förstermann U,
Boissel J-P, Kleinert H. Expressional control of the "constitutive"
isoforms of nitric oxide synthase (NOS I and NOS III).
FASEB J. 1998;12:773–790.
10.
Wallerath T, Witte
K, Schafer SC, Schwarz PM, Prellwitz W, Wohlfart P, Kleinert H, Lehr
HA, Lemmer B, Forstermann U. Down-regulation of the expression of
endothelial NO synthase is likely to contribute to
glucocorticoid-mediated hypertension. Proc
Natl Acad Sci
U S A. 1999;96:13357–13362.
11. Morris SM, Jr, Billiar TR. New insights into the regulation of inducible nitric oxide synthesis. Am J Physiol. 1994;266(pt 1):E829–E839. Review.
12. Ausubel FM, Brent R, Kingston RE, Moore DD, Seidman JG, Smith JA, Struhl K. Current Protocols In Molecular Biology, 2nd ed. New York, NY: Wiley; 1992:2.9.5–2.9.19.
13. Ludbrook J. On making multiple comparisons in clinical and experimental pharmacology and physiology. Clin Exp Pharmacol Physiol. 1991;18:379–392.[Medline] [Order article via Infotrieve]
14. Whitworth JA, Hewitson TD, Ming L, Wilson RS, Scoggins BA, Wright RD, Kincaid-Smith P. Adrenocorticotrophin-induced hypertension in the rat: haemodynamic, metabolic and morphological characteristics. J Hypertens. 1990;8:27–36.[Medline] [Order article via Infotrieve]
15. Ikeda Y, Saito K, Kim J-I, Yokoyama M. Nitric oxide synthase isoform activities in kidney of Dahl salt-sensitive rats. Hypertension. 1995;26(pt 2):1030–1034.
16.
Ahn KY, Mohaupt
MG, Madsen KM, Kone BC. In situ
hybridization localization of mRNA encoding inducible nitric oxide
synthase in rat kidney. Am J
Physiol. 1994;267:F748–F757.
17. Mohaupt MG, Elzie JL, Ahn KY, Clapp WL, Wilcox CS, Kone BC. Differential expression and induction of mRNAs encoding two inducible nitric oxide synthases in rat kidney. Kidney Int. 1994;46:653–665.[Medline] [Order article via Infotrieve]
18. Morrissey JJ, McCracken R, Kaneto H, Vehaskari M, Montani D, Klahr S. Location of an inducible nitric oxide synthase mRNA in the normal kidney. Kidney Int. 1994;45:998–1005.[Medline] [Order article via Infotrieve]
19. Star RA. Intrarenal localization of nitric oxide synthase isoforms and soluble guanylyl cyclase. Clin Exp Pharmacol Physiol. 1997;24:607–610. Review.[Medline] [Order article via Infotrieve]
20. Wu F, Park F, Cowley AW, Mattson DL. Quantification of nitric oxide synthase activity in microdissected segments of the rat kidney. Am J Physiol. 1999;45:F874–F881.
21. Mattson DL, Wu F. Nitric oxide synthase activity and isoforms in rat renal vasculature. Hypertension. 2000;35(pt 2):337–341.
22.
Salazar FJ,
Llinás MT. Role of nitric oxide in the control of sodium excretion.
News Physiol Sci. 1996;11:62–67.
23.
Manning RD Jr, Hu
L. Nitric oxide regulates renal hemodynamics and
urinary sodium excretion in dogs.
Hypertension. 1994;23:619–625.
24. Stoos BA, Garcia NH, Garvin JL. Nitric oxide inhibits sodium reabsorption in the isolated perfused cortical collecting duct. J Am Soc Nephrol. 1995;6:89–94.[Abstract]
25. Garcia NH, Stoos BA, Carretero OA, Garvin JL. Mechanism of the nitric oxide-induced blockade of collecting duct water permeability. Hypertension. 1996;27(pt 2):679–683.
26. Mattson DL, Maeda CY, Bachman TD, Cowley AW. Inducible nitric oxide synthase and blood pressure. Hypertension. 1998;31(pt 1):15–20.
27. Chen PY, Sanders PW. L-arginine abrogates salt-sensitive hypertension in Dahl/Rapp rats. J Clin Invest. 1991;88:1559–1567.
28.
Chen PY, Sanders
PW. Role of nitric oxide synthesis in salt-sensitive hypertension in
Dahl/Rapp rats. Hypertension. 1993;22:812–818.
29.
Ni Z, Oveisi
F, Vaziri ND. Nitric oxide synthase isotype expression in
salt-sensitive and salt-resistant Dahl rats.
Hypertension. 1999;34:552–557.
30.
Rudd MA, Trolliet
M, Hope S, Scribner AW, Daumerie G, Toolan G, Cloutier T, Loscalzo J.
Salt-induced hypertension in Dahl salt-resistant and
salt-sensitive rats with NOS II inhibition.
Am J Physiol. 1999;277:H732–H739.
31. Wen C, Fraser T, Li M, Turner SW, Whitworth JA. Haemodynamic mechanisms of corticotropin (ACTH)-induced hypertension in the rat. J Hypertens. 1999;17:1715–1723.[Medline] [Order article via Infotrieve]
32.
Phillips DIW,
Walker BR, Reynolds RM, Flanagan DEH, Wood PJ, Osmond C, Barker DJP,
Whorwood CB. Low birth weight predicts elevated plasma cortisol
concentrations in adults from 3 populations.
Hypertension. 2000;35:1301–1306.
This article has been cited by other articles:
 |
|
 |
|
  E. Cediel, D. Sanz-Rosa, M. P. Oubina, N. de las Heras, F. R. G. Pacheco, O. Vegazo, J. Jimenez, V. Cachofeiro, and V. Lahera Effect of AT1 receptor blockade on hepatic redox status in SHR: possible relevance for endothelial function? Am J Physiol Regulatory Integrative Comp Physiol, September 1, 2003; 285(3): R674 - R681. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. P.F. Chin-Dusting, B. A. Ahlers, D. M. Kaye, J. J. Kelly, and J. A. Whitworth L-Arginine Transport in Humans With Cortisol-Induced Hypertension Hypertension, June 1, 2003; 41(6): 1336 - 1340. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Y.H. Chan, L.-L. Wang, Y.-M. Chao, and S. H.H. Chan Downregulation of Basal iNOS at the Rostral Ventrolateral Medulla Is Innate in SHR Hypertension, March 1, 2003; 41(3): 563 - 570. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Nishimoto, T. Tomida, H. Matsui, T. Ito, and K. Okumura Decrease in Renal Medullary Endothelial Nitric Oxide Synthase of Fructose-Fed, Salt-Sensitive Hypertensive Rats Hypertension, August 1, 2002; 40(2): 190 - 194. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. T. Alexander, K. Cockrell, F. D. Cline, and J. P. Granger Inducible Nitric Oxide Synthase Inhibition Attenuates Renal Hemodynamics During Pregnancy Hypertension, February 1, 2002; 39(2): 586 - 590. [Abstract] [Full Text] [PDF]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||