Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01185 (vasopressin)
 23,126 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The relative potencies of the argininolytic agents NG-methyl-L-arginine (L-NMA), NG-nitro-L-arginine (L-NNA) and NG-amino-L-arginine (L-NAA) were assayed by their inhibitory effect on both basal and stimulated release of endothelium-derived NO in vitro and in vivo. Basal NO release was indirectly assessed by the ability of the analogs to contract phenylephrine-preconstricted rat aortic rings and their ability to produce a hypertensive response in awake, unanesthetized normotensive rats. In aortic rings, the three analogs induced vasocontraction and inhibited the vasorelaxation mediated by ACh-stimulated endothelial NO release. In this latter assay, L-NNA was 30 times more potent than either L-NMA or L-NAA. In free-moving rats, the agents caused dose-dependent increases in arterial pressure due to the blockade of endogenous NO formation. Dose-response analysis indicated that L-NNA was 87 and 230 times more potent than L-NMA and L-NAA, respectively. Pretreatment with L-NNA was also found to selectively inhibit, but not abolish, the depressor effects of acetylcholine in unanesthetized and phenylephrine- or vasopressin-infused normotensive-pithed rats. These studies indicate that L-NNA is a potent antagonist of endothelium-derived relaxing factor formation in vitro and in vivo. The contractile and hypertensive effects of the argininolytic agents clearly demonstrates that a continuous basal release of endothelium-derived relaxing factor/NO occurs in both isolated vascular rings and whole animals.
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PMID:Comparison of the inhibitory potencies of N(G)-methyl-, N(G)-nitro- and N(G)-amino-L-arginine on EDRF function in the rat: evidence for continuous basal EDRF release. 164 27

The defense of brain volume during hyponatremia cannot be explained by the losses of brain sodium and potassium. We have examined the brain losses of organic osmolytes in rats after 24 h of severe hyponatremia induced by the administration of vasopressin and 5% dextrose in water. Normonatremic controls and animals with intermediate plasma sodium concentration ([Na]) were produced in vasopressin-treated animals by the administration of isocaloric gavages containing varying amounts of NaCl and free water. The animals were killed at 24 h by decapitation, and one brain hemisphere was quickly frozen in liquid nitrogen for organic osmolyte determinations. When compared with controls (plasma [Na] = 139 +/- 1.5 mM), hyponatremic animals (plasma [Na] = 96 +/- 1 mM) had significantly reduced brain contents for sodium, potassium, chloride, glutamate, myo-inositol, N-acetylaspartate, aspartate, creatine, taurine, gamma-aminobutyric acid, and phosphoethanolamine. Plasma [Na] was highly correlated (P < 0.001) with the brain contents for sodium, potassium, and organic osmolytes. Whereas the observed increase in brain water during hyponatremia was only 4.8%, by calculation, brain swelling without brain organic osmolyte losses would have been 11%, an amount that jeopardizes survival.
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PMID:Organic osmolytes in acute hyponatremia. 849 36

Endothelin-1 (ET-1) inhibition of vasopressin (AVP)-stimulated cAMP accumulation in the collecting duct has been hypothesized to be mediated, at least in part, by nitric oxide (NO). To examine this, the effect of ET-1 on NO production by acutely isolated rat inner medullary collecting duct (IMCD) cell suspensions and the role of NO in mediating ET-1 effects on AVP-stimulated cAMP accumulation were studied. ET-1 dose dependently (first evident at 100 pM ET-1) increased IMCD NO production as determined by DAF-FM fluorescence. ET(B) receptor (BQ-788), but not ET(A) receptor (BQ-123), antagonism blocked this effect. Nonspecific NO synthase (NOS) inhibitors [N(G)-nitro-L-arginine methyl ester (L-NAME) or N(G)-monomethyl-L-arginine] or NOS-1 inhibitors (SMTC or VNIO) inhibited the ET-1 response, whereas NOS-2 or NOS-3 inhibitors (L-NAA or 1400W) were ineffective. ET-1 also increased cGMP accumulation. ET-1 caused a 35% reduction in AVP-stimulated cAMP levels; however, this response was not affected by L-NAME or SMTC. The addition of L-arginine, NADPH, tetrahydrobiopterin, or tempol (to reduce superoxide-dependent conversion of NO to peroxynitrate) did not affect the response. NO donors (SNAP or spermine NONOate), at concentrations that stimulated DAF-FM fluorescence and increased cGMP levels, did not alter AVP-stimulated cAMP accumulation in the IMCD cell suspensions. In conclusion, ET-1 stimulates IMCD NO production through activation of the ET(B) receptor and NOS-1. However, neither ET-1-mediated NO production nor NO donors inhibit AVP-stimulated cAMP accumulation, indicating that NO does not mediate ET-1 inhibition of cAMP production by the IMCD.
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PMID:Endothelin-1 stimulates NO production and inhibits cAMP accumulation in rat inner medullary collecting duct through independent pathways. 1638 Apr 57