Treatment with tetrahydrobiopterin reduces blood pressure in male SHR by reducing testosterone synthesis

2005 ◽  
Vol 288 (3) ◽  
pp. R733-R736 ◽  
Author(s):  
Lourdes A. Fortepiani ◽  
Jane F. Reckelhoff
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
Mean Arterial Pressure ◽  
Spontaneously Hypertensive Rats ◽  
Serum Testosterone ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive ◽  
Testosterone Biosynthesis ◽  
Dependent Model ◽  
Testosterone Synthesis

Treatment with tetrahydrobiopterin (BH4) reduces blood pressure in spontaneously hypertensive rats (SHR). In the present study, we tested the hypothesis that chronic BH4 reduces blood pressure in male SHR by reducing testosterone biosynthesis mediated by increasing nitric oxide (NO). Male SHR, aged 17–18 wk, intact or castrated, were treated for 1 wk with BH4 (20 mg·kg−1·day−1 ip). After 1 wk, mean arterial pressure (MAP), serum testosterone, and nitrate/nitrite excretion (NO x) were measured. MAP was significantly higher in intact males than castrated males (179 ± 2 vs. 155 ± 4 mmHg, P < 0.001). In intact males, BH4 caused a 17% reduction in MAP (148 ± 2 mmHg), had no effect on NO x, and reduced serum testosterone by 85% (24.09 ± 2.37 vs. 3.72 ± 0.73 ng/dl; P < 0.001). In castrated males, BH4 had no effect on MAP (152 ± 5 mmHg) but increased NO x by 38%. When castrated males were supplemented with testosterone, MAP increased to the same level as in intact males (180 ± 7 mmHg), and BH4 had no effect on MAP (182 ± 7 mmHg) or NO x. NO has been shown to decrease testosterone biosynthesis. Chronic sodium nitrite (70 mg·kg−1·day−1 × 1 wk) decreased MAP in intact males (150 ± 4 mmHg) but had no effect on serum testosterone (21.46 ± 3.08 ng/dl). The data suggest that BH4 reduces testosterone synthesis and thereby reduces MAP in male SHR, an androgen-dependent model of hypertension. The mechanism(s) by which BH4 reduces serum testosterone levels are not clear, but the data do not support a role for NO as a mediator.

Contribution of Vascular Nitric Oxide to Basal Blood Pressure in Conscious Spontaneously Hypertensive Rats and Normotensive Wistar Kyoto Rats

1995 ◽  
Vol 89 (2) ◽  
pp. 177-182 ◽  
Author(s):  
Naoyoshi Minami ◽  
Yutaka Imai ◽  
Jun-Ichiro Hashimoto ◽  
Keishi Abe
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
Mean Arterial Pressure ◽  
Methyl Ester ◽  
Spontaneously Hypertensive Rats ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive ◽  
Wistar Kyoto Rats ◽  
Basal Blood Pressure ◽  
Wistar Kyoto

1. The aim of this study was to clarify the extent to which vascular nitric oxide contributes to basal blood pressure in conscious spontaneously hypertensive rats and normotensive Wistar Kyoto rats. 2. The contribution of vascular nitric oxide to maintenance of blood pressure was estimated by measuring the pressor response to an intravenous injection of nitric oxide synthase inhibitor, Nω-l-arginine methyl ester, given after serial injections of captopril, vasopressin V1-receptor antagonist (V1-antagonist) and ganglion blocker (pentolinium) in conscious spontaneously hypertensive and Wistar Kyoto rats aged 20–28 weeks. To estimate the ‘amplifier property’ of hypertrophied vasculature in spontaneously hypertensive rats, which is known to modulate pressor responses, the lower blood pressure plateau after serial injections of captopril, V1-antagonist and pentolinium and the maximum blood pressure elicited by subsequent injection of increasing doses of phenylephrine were also measured. 3. The serial injections of captopril, V1-antagonist and pentolinium decreased mean arterial pressure from 164 ± 9 mmHg to 67 ± 2 mmHg and from 117 ± 2 mmHg to 49 ± 1 mmHg in spontaneously hypertensive and Wistar Kyoto rats respectively. The subsequent injection of Nω-l-arginine methyl ester restored mean arterial pressure almost to its control levels in both spontaneously hypertensive and Wistar Kyoto rats. The absolute changes in mean arterial pressure elicited by Nω-l-arginine methyl ester were significantly greater in spontaneously hypertensive than in Wistar Kyoto rats (P < 0.01), but there was no significant difference in the responses to Nω-l-arginine methyl ester when they were expressed as percentages of either the lower blood pressure plateau or maximum blood pressure. 4. These results indicate that basal blood pressure in both spontaneous hypertensive and Wistar Kyoto rats is maintained by a balance between vascular nitric oxide and major pressor systems. They also suggest that the vasodilatory effect of vascular nitric oxide does not differ between spontaneously hypertensive and Wistar Kyoto rats, and that the increased pressor effect of Nω-l-arginine methyl ester in spontaneously hypertensive rats is due to a vascular amplifier mechanism.

Abstract 440: Female Spontaneously Hypertensive Rats are More Dependent on Nitric Oxide in Modulating Blood Pressure and Renal Injury Than Males

Hypertension ◽  
2012 ◽  
Vol 60 (suppl_1) ◽  
Author(s):  
Ahmed A Elmarakby ◽  
Chelsey Pye ◽  
Krystal Brinson ◽  
Tatsuo Yamamoto ◽  
Jennifer C Sullivan
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
T Cell ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Renal Injury ◽  
Spontaneously Hypertensive Rats ◽  
Hypertensive Rats ◽  
Monocyte Chemoattractant Protein 1 ◽  
Spontaneously Hypertensive

We recently demonstrated that female spontaneously hypertensive rats (SHR) have higher nitric oxide (NO) bioavailability in the kidney compared to males. Therefore, we hypothesize that female SHR are more dependent on the NO synthase (NOS) system to modulate their blood pressure, and as a result will have a greater rise in blood presure and renal injury in response to chronic NOS inhibition compared to males. Mean arterial pressure in SHR was very sensitive to NOS inhibition, with both sexes exhibiting a significant increase in blood pressure to the non-specific NOS inhibitor N G -nitro-L-arginine methyl ester (L-NAME) at a dose of 2 mg/kg/day. However, there was not a sex difference in the percent increase in mean arterial pressure. Treatment of female and male SHR with 7 mg/kg/day L-NAME for 2 weeks significantly increased mean arterial pressure and indices of renal injury in both females and males; the percent increases in mean arterial pressure and injury were greater in females during the last three days of L-NAME treatment (% increase in mean arterial pressure was 44± 1.3 in females vs. 35± 2.9 in males, P<0.05). L-NAME treatment also increased indices of inflammation and oxidative stress as urinary monocyte chemoattractant protein-1 (MCP-1) and thiobarbituric acid reactive substances (TBARs) excretion levels were increased by L-NAME; however, the increases were greater in females. Renal cortical macrophage and T cell infiltrations and soluble intracellular adhesion molecule-1 (sICAM-1) were also elevated following L-NAME treatment (cortical sICAM-1 levels increased from 4.7± 0.2 to 9± 0.1 ng/mg in males vs. 4.6± 0.1 to 7.9± 0.3 ng/mg in females, P<0.05). Although renal cortical macrophage infiltration was greater in female SHR vs. males following L-NAME treatment, the increase in cortical T cell infiltration and sICAM-1 were greater in males. These data suggest that the NO system plays an important role in modulating blood pressure, renal injury and inflammation in SHR, with females being more dependent on the NOS system than males.

scholarly journals Increased Blood Pressure Causes Lymphatic Endothelial Dysfunction via Oxidative Stress in Spontaneously Hypertensive Rats

Hypertension ◽  
2020 ◽  
Vol 76 (2) ◽  
pp. 598-606
Author(s):  
Masashi Mukohda ◽  
Risuke Mizuno ◽  
Hiroshi Ozaki
Keyword(s):  
Oxidative Stress ◽  
Nitric Oxide ◽  
Blood Pressure ◽  
Endothelial Dysfunction ◽  
Nadph Oxidase ◽  
Sodium Nitroprusside ◽  
P38 Mapk ◽  
Spontaneously Hypertensive Rats ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive

The lymphatic system is involved in the pathogenesis of edema, inflammation, and cancer metastasis. Because lymph vessels control fluid electrolytes and volume balance, changes in lymphatic activity can be expected to alter systemic blood pressure. This study examined possible changes in lymphatic contractile properties in spontaneously hypertensive rats (SHR). Thoracic ducts isolated from 10- to 12-week-old SHR exhibited either decreased acetylcholine-induced endothelium-dependent relaxation or sodium nitroprusside-induced endothelium-independent relaxation compared with age-matched Wister-Kyoto rats. The impairment in acetylcholine responsiveness was more pronounced than sodium nitroprusside responsiveness. N-Nitro-L-arginine methyl ester, a nitric oxide synthase inhibitor blunted acetylcholine-induced relaxation in Wister-Kyoto rats, indicating an involvement of endothelial nitric oxide production. Endothelial dysfunction in lymph vessels of SHR was attenuated by tempol (a superoxide dismutase mimetic), apocynin, or VAS-2870 (NADPH oxidase inhibitors). Consistent with these observations, nitrotyrosine levels were significantly elevated in SHR, indicative of increased oxidative stress. In addition, protein expression of NADPH oxidase 2 and phosphorylation of p47 phox (Ser345) were significantly increased in SHR. Further, SB203580 (a p38 MAPK inhibitor) restored the acetylcholine-induced relaxation in SHR. It is notable that 4-week-old SHR, which exhibited normal blood pressure, did not show any decreased activity of acetylcholine- or sodium nitroprusside-induced relaxation. Additionally, antihypertensive treatment of 4-week-old SHR with hydrochlorothiazide and reserpine or hydrochlorothiazide and hydralazine for 6 weeks completely restored lymphatic endothelial dysfunction. We conclude that contractile activity of lymphatic vessels is functionally impaired with the development of increasing blood pressure, which is mediated through increased oxidative stress via the p38 MAPK/NADPH oxidase 2 pathway.

scholarly journals Evidence that Nitric Oxide is Involved in the Blood Pressure Lowering Effect of the Peptide AVFQHNCQE in Spontaneously Hypertensive Rats

Nutrients ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 225 ◽  
Author(s):  
Anna Mas-Capdevila ◽  
Lisard Iglesias-Carres ◽  
Anna Arola-Arnal ◽  
Gerard Aragonès ◽  
Amaya Aleixandre ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
Oral Administration ◽  
Spontaneously Hypertensive Rats ◽  
Protein Hydrolysate ◽  
Antioxidant Properties ◽  
Hypertensive Rats ◽  
Blood Pressure Lowering Effect ◽  
Spontaneously Hypertensive ◽  
Lowering Effect

AVFQHNCQE is an antihypertensive nonapeptide obtained from a chicken foot protein hydrolysate. The present study aims to investigate the mechanisms involved in its blood pressure (BP)-lowering effect. Male (17–20 weeks old) spontaneously hypertensive rats (SHR) were used in this study. Rats were divided into two groups and orally administered water or 10 mg/kg body weight (bw) AVFQHNCQE. One hour post-administration, animals of both groups were intra-peritoneally treated with 1 mL of saline or with 1 mL of saline containing 30 mg/kg bw Nω-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide (NO) synthesis, or with 1 mL of saline containing 5 mg/kg bw indomethacin, which is an inhibitor of prostacyclin synthesis (n = 6 per group). Systolic BP was recorded before oral administration and six hours after oral administration. In an additional experiment, SHR were administered water or 10 mg/kg bw AVFQHNCQE (n = 6 per group) and sacrificed six hours post-administration to study the mechanisms underlying the peptide anti-hypertensive effect. Moreover, the relaxation caused by AVFQHNCQE in isolated aortic rings from Sprague-Dawley rats was evaluated. The BP-lowering effect of the peptide was not changed after indomethacin administration but was completely abolished by L-NAME, which demonstrates that its anti-hypertensive effect is mediated by changes in endothelium-derived NO availability. In addition, AVFQHNCQE administration downregulated aortic gene expression of the vasoconstrictor factor endothelin-1 and the endothelial major free radical producer NADPH. Moreover, while no changes in plasma ACE activity were observed after its administration, liver GSH levels were higher in the peptide-treated group than in the water group, which demonstrates that AVFQHNCQE presents antioxidant properties.

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