scholarly journals Systemic hypotensive effects of testosterone are androgen structure-specific and neuronal nitric oxide synthase-dependent

2015 ◽  
Vol 309 (2) ◽  
pp. R189-R195 ◽  
Author(s):  
Mercedes Perusquía ◽  
Clayton D. Greenway ◽  
Lisa M. Perkins ◽  
John N. Stallone
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Neuronal Nitric Oxide Synthase ◽  
Sprague Dawley ◽  
Peripheral Vasculature ◽  
Similar Reduction ◽  
Arterial Blood ◽  
Sd Rats ◽  
Oxide Synthase

Testosterone (TES) and other androgens exert a direct vasorelaxing action on the vasculature in vitro that is structurally specific and independent of cytosolic androgen receptor (AR). The effects of intravenous androgen infusions on mean arterial blood pressure (BP) and heart rate (HR) were determined in conscious, unrestrained, chronically catheterized, ganglionically blocked (hexamethonium, HEX; 30 mg/kg ip) male Sprague-Dawley (SD) and testicular-feminized male (Tfm; AR-deficient) rats, 16–20 wk of age. BP and HR were recorded at baseline and with increasing doses of androgens (0.375–6.00 μmol·kg−1·min−1 iv; 10 min/dose). Data are expressed as means ± SE ( n = 5–8 rats/group). In SD rats, baseline BP and HR averaged 103 ± 4 mmHg and 353 ± 12 beats/min (bpm). TES produced a dose-dependent reduction in BP to a low of 87 ± 4 mmHg (Δ16%), while HR was unchanged (354 ± 14 bpm). Neither BP (109 ± 3 mmHg) nor HR (395 ± 13 bpm) were altered by vehicle (10% EtOH in 0.9% saline; 0.15 ml·kg−1·min−1, iv). In Tfm, TES produced a similar reduction in BP (99 ± 3 to 86 ± 3 mmHg, Δ13%); HR was unchanged (369 ± 18 bpm). In SD, 5β-dihydrotestosterone (genomically inactive metabolite) produced a greater reduction in BP than TES (102 ± 2 to 79 ± 2 mmHg, Δ23%); HR was unchanged (361 ± 9). A 20-μg iv bolus of sodium nitroprusside in both SD and Tfm rats reduced BP 30–40 mmHg, while HR was unchanged, confirming blockade by HEX. Pretreatment of SD rats with neuronal nitric oxide synthase (nNOS) inhibitor (S-methyl-thiocitrulline, SMTC; 20 μg·kg−1·min−1 × 30 min) abolished the hypotensive effects of TES infusion on BP (104 ± 2 vs. 101 ± 2 mmHg) and HR (326 ± 11 vs. 324 ± 8 bpm). These data suggest the systemic hypotensive effect of TES and other androgens involves a direct vasodilatory action on the peripheral vasculature which, like the effect observed in isolated arteries, is structurally specific and AR-independent, and involves activation of nNOS.

Neuronal nitric oxide synthase modulates rat renal microvascular function

1998 ◽  
Vol 274 (3) ◽  
pp. F516-F524 ◽  
Author(s):  
Atsuhiro Ichihara ◽  
Edward W. Inscho ◽  
John D. Imig ◽  
L. Gabriel Navar
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Neuronal Nitric Oxide Synthase ◽  
Macula Densa ◽  
Ang Ii ◽  
Sprague Dawley ◽  
Vasoconstrictor Response ◽  
Arteriolar Tone ◽  
Oxide Synthase

This study was performed to determine the influence of neuronal nitric oxide synthase (nNOS) on renal arteriolar tone under conditions of normal, interrupted, and increased volume delivery to the macula densa segment and on the microvascular responses to angiotensin II (ANG II). Experiments were performed in vitro on afferent (21.2 ± 0.2 μm) and efferent (18.5 ± 0.2 μm) arterioles of kidneys harvested from male Sprague-Dawley rats, using the blood-perfused juxtamedullary nephron technique. Superfusion with the specific nNOS inhibitor, S-methyl-l-thiocitrulline (l-SMTC), decreased afferent and efferent arteriolar diameters, and these decreases in arteriolar diameters were prevented by interruption of distal volume delivery by papillectomy. When 10 mM acetazolamide was added to the blood perfusate to increase volume delivery to the macula densa segment, afferent arteriolar vasoconstrictor responses tol-SMTC were enhanced, but this effect was again completely prevented after papillectomy. In contrast, the arteriolar diameter responses to the nonselective NOS inhibitor, N ω-nitro-l-arginine (l-NNA) were only attenuated by papillectomy.l-SMTC (10 μM) enhanced the efferent arteriolar vasoconstrictor response to ANG II but did not alter the afferent arteriolar vasoconstrictor responsiveness to ANG II. In contrast, l-NNA (100 μM) enhanced both afferent and efferent arteriolar vasoconstrictor responses to ANG II. These results indicate that the modulating influence of nNOS on afferent arteriolar tone of juxtamedullary nephrons is dependent on distal tubular fluid flow. Furthermore, nNOS exerts a differential modulatory action on the juxtamedullary microvasculature by enhancing efferent, but not afferent, arteriolar responsiveness to ANG II.

Abstract 085: CHIP: E3 Ubiquitin Ligase Mediates Proteasomal Degradation of Neuronal Nitric Oxide Synthase in the Paraventricular Nucleus of Rats with Heart Failure

Hypertension ◽  
2017 ◽  
Vol 70 (suppl_1) ◽  
Author(s):  
Neeru M Sharma ◽  
Kenichi Katsurada ◽  
Xuefei Liu ◽  
Kaushik P Patel
Keyword(s):  
Nitric Oxide ◽  
Heart Failure ◽  
Nitric Oxide Synthase ◽  
Paraventricular Nucleus ◽  
Ubiquitin Ligase ◽  
Protein A ◽  
Neuronal Nitric Oxide Synthase ◽  
Proteasomal Degradation ◽  
Oxide Synthase

The exaggerated sympathetic drive is a characteristic of heart failure (HF) due to reduced neuronal nitric oxide synthase (nNOS) within the paraventricular nucleus (PVN). Previously we have shown that there were increased accumulation of nNOS-ubiquitin (nNOS-Ub) conjugates in the PVN of rats with HF (1.0±0.05 Sham vs. 1.29±0.06 HF) due to the increased levels of PIN (a protein inhibitor of nNOS, known to dissociate nNOS dimers into monomers) (0.76±0.10 Sham vs. 1.12±0.09 HF) and decreased levels of tetrahydrobiopterin (BH4): a cofactor required for stabilization of nNOS dimers (0.62±0.02 Sham vs. 0.44±0.03 HF). We also showed that there is blunted nitric oxide-mediated inhibition of sympathetic tone via the PVN in HF. Here we examined whether CHIP(C-terminus of Hsp70 -interacting protein), a chaperone-dependent E3 ubiquitin-protein isopeptide ligase known to ubiquitylate Hsp90-chaperoned proteins could act as an ubiquitin ligase for nNOS in the PVN. Immunofluorescence studies revealed colocalization of nNOS and CHIP in the PVN indicating their possible interaction. CHIP expression was increased by 50% in the PVN of rats with HF(0.96±0.08 Sham vs.1.44±0.10* HF). It is shown that Hsp90 protects nNOS from ubiquitination while Hsp70 promotes the ubiquitination and degradation. We observed significant upregulation of Hsp70 (0.49±0.03 Sham vs. 0.65±0.02* HF) with a trend toward the decrease in Hsp90 expression (0.90±0.07 Sham vs. 0.71±0.06 HF). The opposing effects of the two chaperones could account for the increased CHIP-mediated ubiquitination and degradation of dysfunctional nNOS monomers in the PVN of rats with HF. Furthermore, neuronal NG108-15 cell line transfected with the pCMV3-CHIP-GFP spark (CHIP overexpression plasmid) showed approximately 74% increase in CHIP with concomitant 49% decrease in nNOS expression. In vitro ubiquitination assay in NG108 cells transfected with pCMV-(HA-Ub) 8 and pCMV3-CHIP-GFP spark plasmid reveal increased HA-Ub-nNOS conjugates (1.13 ± 0.09 Scramble vs. 1.65 ± 0.12* CHIP plasmid). Taken together, our results identify CHIP as an E3 ligase for ubiquitination of dysfunctional nNOS and CHIP expression is augmented during HF leading to increased proteasomal degradation of nNOS in the PVN.

Abstract 271: Nos1ap Alters Qtc Intervals Upon Overexpression in Mice

2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Tatjana Williams ◽  
Daniel Oppelt ◽  
Anahi Paula Arias-Loza ◽  
Marco Abesser ◽  
Joachim Schmitt ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Sudden Cardiac Death ◽  
Nitric Oxide Synthase ◽  
Cardiac Death ◽  
Association Studies ◽  
Neuronal Nitric Oxide Synthase ◽  
Genetic Alterations ◽  
Programmed Stimulation ◽  
Oxide Synthase

Rationale: The QT interval duration (QTc) reflects cardiac depolarization. It may predispose individuals to ventricular tachycardia and sudden cardiac death if prolonged (long QTc), shortened (short QTc) or otherwise unregularly. Whole-genome association studies have linked genetic variations in the neuronal nitric oxide synthase adapter protein NOS1AP to variations in QTc intervals and sudden cardiac death. Hypothesis: We hypothesize NOS1AP functions as an L-type-Ca2+ channel modulator via its interaction with the neuronal nitric oxide synthase NOS1. Therefore, alterations in myocardial NOS1AP expression should temper with QTc intervals and increase susceptibility to rhythm disorders. Methods and results: We generated conditional double transgenic mice by crossbreeding pTRE-6xHN-Nos1AP animals with α-MHC-tTA mice; NOS1AP expression is therefore restricted to cardiomyocytes and under control of doxycycline (Tet-Off system). Double transgenic animals were investigated with the main focus upon electrical alterations. Heart rates were similar in NOS1AP overexpressing and non-induced animals. Atrial programmed stimulation repeatedly caused atrial tachycardia, while ventricular programmed stimulation caused VT in NOS1AP overexpressing mice. There was a clear decrease of QTc intervals in NOS1AP overexpressing mice paralleld by a significantly reduced survival (only 56% after 12 weeks vs 100% in non-induced mice. Induced QTc alterations and accompanied deaths subsided upon readministration of doxycycline. We also investigated the functional effect of the human SNP rs16847548 (T/C). We found that this SNP decreased NOS1AP transcriptional activity in vitro and therefore suggest this leads to a decrease in NOS1AP expression in humans. Conclusion: Myocardial overexpression of NOS1AP leads to short QTc syndrome with increased susceptibility to atrial and ventricular rhythm disorders and cardiac death. SNP rs16847548 in NOS1AP resulted in less NOS1AP promoter activity in vitro which could explain the alteration in QTc intervals. In summary, not only mutations in ion channels themselves but also genetic alterations in the expression of ion channel modulators such as NOS1AP, have an impact on QTc intervals.

scholarly journals The NOS Inhibitor, 7-Nitroindazole, Decreases Focal Infarct Volume but Not the Response to Topical Acetylcholine in Pial Vessels

1994 ◽  
Vol 14 (6) ◽  
pp. 924-929 ◽  
Author(s):  
Tazuka Yoshida ◽  
Volker Limmroth ◽  
Katsumi Irikura ◽  
Michael A. Moskowitz
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Infarct Volume ◽  
Ischemic Injury ◽  
Sprague Dawley ◽  
Arterial Blood ◽  
Mca Occlusion ◽  
Permanent Occlusion ◽  
Nos Inhibitor ◽  
Oxide Synthase

We examined whether 7-nitroindazole (7-NI), a putative inhibitor of neuronal nitric oxide synthase (nNOS), decreases cerebral infarction 24 h after proximal middle cerebral artery (MCA) occlusion. In preliminary experiments, we determined that 7-NI (25, 50, and 100 mg/kg i.p.) decreased nitric oxide synthase (NOS) activity within cerebral cortex by 40–60% when measured up to 120 min, but not 240 min after administration. At 25 or 50 mg/kg, 7-NI did not alter the systemic arterial blood pressure or the dilation of pial arterioles after topical acetylcholine (10 and 100 μ M). To examine the effect of 7-NI on infarct size, 55 Sprague–Dawley halothaneanesthetized rats were subjected to proximal MCA occlusion (modified Tamura method). Five minutes after occlusion, 7-NI (25 or 50 mg/kg i.p.) or vehicle was injected. Animals treated with 25 or 50 mg/kg showed 25 and 27% reductions in infarct volume, respectively. Coadministration of l-arginine (300 mg/kg i.p.) plus 7-NI (25 mg/kg i.p.) reversed the effect. If, indeed, the effects of 7-NI are mediated by inhibition of nNOS activity, these results suggest that enzymatic products of the neuronal isoform promote ischemic injury and that they do so at least within the first few hours after permanent occlusion. The results also emphasize the importance of developing strategies to selectively inhibit the neuronal isoform inasmuch as we observed previously that administering the less selective NOS inhibitor, Nω-nitro-l-arginine (L-NA), in the same model either caused no change or increased the volume of ischemic injury.

Ubiquitination and Degradation of Neuronal Nitric-Oxide Synthase in Vitro: Dimer Stabilization Protects the Enzyme from Proteolysis

2004 ◽  
Vol 66 (4) ◽  
pp. 964-969 ◽  
Author(s):  
Anwar Y. Dunbar ◽  
Yasuhiko Kamada ◽  
Gary J. Jenkins ◽  
Ezra R. Lowe ◽  
Scott S. Billecke ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Neuronal Nitric Oxide Synthase ◽  
Oxide Synthase

scholarly journals Role of Sex Hormones and Their Receptors on Gastric Nrf2 and Neuronal Nitric Oxide Synthase Function in an Experimental Hyperglycemia Model

2020 ◽  
Author(s):  
Jeremy Sprouse ◽  
Chethan Sampath ◽  
PANDU GANGULA
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Sex Hormones ◽  
Hormone Receptors ◽  
Neuronal Nitric Oxide Synthase ◽  
Nitrite Production ◽  
Oxide Synthase ◽  
Nnos Expression

Abstract Background: Gastroparesis, a condition of abnormal gastric emptying, is most commonly observed in diabetic women. To date, the role of ovarian hormones and/or gastric hormone receptors on regulating nitrergic-mediated gastric motility remains inconclusive. Aim: The purpose of this study is to investigate whether sex hormones/their receptors can attenuate altered Nuclear factor (erythroid-derived 2)-like 2 (Nrf2), neuronal Nitric Oxide Synthase (nNOS) expression and nitrergic relaxation in gastric neuromuscular tissues exposed to in-vitro hyperglycemia (HG). Methods: Gastric neuromuscular sections from adult female C57BL/6J mice were incubated in normoglycemic (NG, 5mM) or hyperglycemic (30 mM or 50 mM) conditions in the presence or absence of selective estrogen receptor (ER) agonists (ERα /PPT or ERβ: DPN); or non-selective sex hormone receptor antagonists (ER/ICI 182,780, or progesterone receptor (PR)/ RU486) for 48 hours. mRNA, protein expression and nitrergic relaxation of circular gastric neuromuscular strips were assessed. Results: Our findings in HG, compared to NG, demonstrate a significant reduction in ER, Nrf2, and nNOS expression in gastric specimens. In addition, in-vitro treatment with sex hormones and/or their agonists significantly (*p<0.05) restored Nrf2/nNOSα expression and total nitrite production. Conversely, ER, but not PR, antagonist significantly reduced Nrf2/nNOSα expression and nitrergic relaxation. Conclusions: Our data suggest that ER’s can regulate nitrergic function by improving Nrf2/nNOS expression in experimental hyperglycemia.

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