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)

We have studied the effect of the alkaloid berberine on the contraction of guinea pig aortic strips induced by various stimuli. Berberine (25-200 microM) inhibited the response of the strips to norepinephrine and histamine, but did not decrease the high K(+)-elicited contraction. The antagonism of berberine was not competitive because in the presence of the alkaloid, maximum response to agonists could not be obtained. Analysis of the drug's effect on the time course of norepinephrine-induced contraction showed that berberine reduced both the rate and the relative contribution to developed tension of the initial, rapid phase, whereas the slow, later component was less affected. Berberine inhibited the response of aortic strips incubated in 0 mM Ca++ to norepinephrine, but did not reduce caffeine-induced contraction and also inhibited phospholipase C-activated contractile response, which has been ascribed to production of inositol phosphate-3 in smooth muscle cells. In cultured arterial smooth muscle cells (A7r5 line), the alkaloid did not significantly decrease the production of inositol phosphates activated by Arg8-vasopressin. The pattern of berberine action is difficult to reconcile with an involvement of the contractile machinery and suggests that the drug has no effect on the voltage-operated calcium channels. Although an antagonism at the receptors or an increase of cyclic AMP or cyclic GMP cannot be completely excluded, we suggest that at least one component of the berberine inhibitory effect may be due to its action on some step of the chain of events linking receptors to contractile response.
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PMID:On the mechanism of vasodilating action of berberine: possible role of inositol lipid signaling system. 156 Mar 77

We tested the hypothesis that increased systemic vascular resistance in spontaneously hypertensive rats may be secondary to enhanced phospholipase C activity in response to vasoconstrictor stimuli. Activation of phospholipase C by angiotensin II (Ang II), thromboxane A2, arginine vasopressin, and endothelin-1 was compared in cultured glomerular mesangial cells and mesenteric vascular smooth muscle cells taken from 13- to 14-week-old hypertensive and normotensive Wistar-Kyoto rats (blood pressure, 185 +/- 1 versus 135 +/- 2 mm Hg). Phospholipase C was assessed by measuring cytosolic free calcium and by the accumulation of radiolabeled inositol phosphates. Basal cytosolic calcium did not differ between mesangial cells taken from both strains but was greater in smooth muscle cells from hypertensive rats (210.1 +/- 8.2 versus 149.2 +/- 4.7 nM). The responsiveness of cytosolic calcium and inositol phosphate accumulation to Ang II was significantly enhanced in mesangial cells from hypertensive rats (10(-7) M Ang II: peak increase of calcium, 1,266 +/- 181 versus 603 +/- 93 nM; percent increment of inositol phosphates at 1 minute, 266 +/- 26 versus 98 +/- 10%). Vascular smooth muscle cells from hypertensive rats, when compared with normotensive rats, showed a similar augmentation of Ang II-stimulated intracellular calcium and inositol phosphates. Thromboxane A2-induced enhancement of intracellular calcium and inositol phosphate accumulation in vascular smooth muscle cells was also greater in hypertensive animals. However, the responses to vasopressin and endothelin in mesangial or vascular smooth muscle cells did not differ between the normotensive and hypertensive animals. There was no significant difference in Ang II receptor number and affinity between hypertensive- and normotensive-derived mesangial cells. We conclude that genetically increased blood pressure in rats may be secondary to enhanced post-receptor signaling in glomerular mesangial cells activated by Ang II and to enhanced signaling in vascular smooth muscle cells stimulated by either Ang II or thromboxane A2.
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PMID:Phospholipase C responses in cells from spontaneously hypertensive rats. 156 63

Prolonged treatment of quiescent Swiss 3T3 cells with vasopressin induced heterologous desensitization of specific early signals stimulated by platelet-derived growth factor (PDGF). PDGF caused a striking dose-dependent release of [3H]arachidonic acid (EC50 = 2 ng/ml) and prostaglandin E2 (EC50 = 5 ng/ml). These responses are severely attenuated (greater than 85%) by prior exposure to vasopressin in a dose-dependent manner (IC50 = 1.5 nM). Maximal loss of responsiveness occurred after 40 h of vasopressin treatment with a half-maximal desensitization after 11-13 h. The desensitization is dependent upon binding to the V1 receptor, since it can be prevented by the antagonist [Pmp1,O-Me-Tyr2,Arg8]vasopressin. In contrast, stimulation of inositol phosphate accumulation and production of diacylglycerol and phosphatidic acid by PDGF are unchanged. Thus, the observed heterologous desensitization cannot be attributed to an inability to activate phospholipase C. Furthermore, prior exposure to vasopressin did not affect the ability of PDGF to evoke tyrosine phosphorylation of cellular substrates, demonstrating that vasopressin-induced heterologous desensitization causes a block at a point distal to activation of receptor tyrosine kinase activity. Other downstream responses including transient induction of c-fos expression and stimulation of DNA synthesis were attenuated by vasopressin pretreatment. The findings demonstrate a novel mechanism of heterologous cellular desensitization namely, persistent occupancy of a guanine nucleotide-binding protein-coupled receptor, like the V1 type vasopressin receptor, attenuates responsiveness to a polypeptide growth factor like PDGF that initiates responses through a tyrosine kinase receptor.
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PMID:Heterologous desensitization of platelet-derived growth factor-mediated arachidonic acid release and prostaglandin synthesis. 163 51

The mitogenic neuropeptides bombesin and vasopressin markedly increased tyrosine and serine phosphorylation of multiple substrates in quiescent Swiss 3T3 fibroblasts, including two major bands of Mr 90,000 and 115,000. Tyrosine phosphorylation of these proteins was increased as judged by immunoprecipitation of 32Pi-labeled cells and immunoblotting of unlabeled cells with monoclonal antiphosphotyrosine antibodies, elution with phenyl phosphate, and phospho amino acid analysis. Phosphotyrosyl proteins generated by bombesin and vasopressin did not correspond either by apparent molecular weight or by immunological and biochemical criteria to several known tyrosine kinase substrates, including phospholipase C gamma, the microtubule-associated protein 2 kinase, GTPase-activating protein, or phosphatidylinositol kinase. The effect was rapid (within seconds), concentration dependent, and inhibited by specific receptor antagonists for both bombesin and vasopressin. The endothelin-related peptide, vasoactive intestinal contractor, also elicited a rapid and concentration-dependent tyrosine/serine phosphorylation of a similar set of substrates. These results demonstrate that neuropeptides, acting through receptors linked to GTP-binding proteins, stimulate tyrosine phosphorylation of a common set of substrates in quiescent Swiss 3T3 cells and suggest the existence of an additional signal transduction pathway in neuropeptide-induced mitogenesis.
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PMID:Bombesin, vasopressin, and endothelin rapidly stimulate tyrosine phosphorylation in intact Swiss 3T3 cells. 164 10

Preincubation of rat liver cells (the C-9 cell line) with okadaic acid (0.6 microM), a known inhibitor of protein-serine/threonine phosphate phosphatases 2A and 1, for 30 min amplified 6-keto-PGF1 alpha production stimulated by thapsigargin, thrombin, platelet activating factor (PAF), 12-O-tetradecanoylphorbol-13-acetate (TPA), the Ca2+ ionophore A-23187 and lysine-vasopressin (Lys.ADH) but not that stimulated by exogenous arachidonic acid. The amplification occurred within minutes after addition of the stimulators. The effect of preincubation was time dependent. Preincubation of the cells with okadaic acid (0.6 microM) for longer than 30 min decreased this amplification. The results suggest that inhibition of protein-serine/threonine phosphate phosphatase(s) can both positively and negatively regulate deesterification of phospholipids although the negative regulation may reflect a toxic response. Microcystin LR and nodularin, inhibitors of protein-serine/threonine phosphate phosphatases 2A and 1 in vitro, did not amplify 6-keto-PGF1 alpha production by PAF when incubated with intact cells.
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PMID:Effects of okadaic acid on agonist-stimulated PGI2 production by rat liver cells (the C-9 cell line). 164 47

The subcellular distribution of 45Ca2+ accumulated by isolated rat hepatocytes exposed to dibutyryl cyclic AMP (dbcAMP) followed by vasopressin (Vp) was studied by means of a nondisruptive technique. When treated with dbcAMP followed by vasopressin, hepatocytes obtained from fed rats accumulated an amount of Ca2+ approximately fivefold higher than that attained under control conditions. Ca2+ released from the mitochondrial compartment by the uncoupler carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP) accounted for only a minor portion of the accumulated Ca2+. The largest portion was released by the Ca2+ ionophore A23187 and was attributable to a nonmitochondrial compartment. DbcAMP + Vp-treatment also caused a maximal stimulation of glucose production and a twofold increase in cellular glucose 6-phosphate levels. In hepatocytes obtained from fasted rats, dbcAMP + Vp-stimulated Ca2+ accumulation was lower, although with the same subcellular distribution, and was associated with a minimal glucose production. In the presence of gluconeogenetic substrates (lactate plus pyruvate) hepatocytes from fasted rats were comparable to cells isolated from fed animals. However, Ca2+ accumulation and glucose 6-phosphate production could be dissociated in the absence of dbcAMP, in the presence of lactate/pyruvate alone. Under this condition in fact Vp induced only a minimal accumulation of Ca2+ in hepatocytes isolated from fasted rats, although glucose production was markedly increased. Moreover, treatment of fed rat hepatocytes with 1 mM ATP caused a maximal activation of glycogenolysis, but only a moderate stimulation of cellular Ca2+ accumulation. In this case, sequestration of Ca2+ occurred mainly in the mitochondrial compartment. By contrast, the addition of ATP to dbcAMP-pretreated hepatocytes induced a large accumulation of Ca2+ in a nonmitochondrial pool. Additional experiments using the fluorescent Ca2+ indicator Fura-2 showed that dbcAMP pretreatment can enlarge and prolong the elevation of cytosolic free Ca2+ caused by Vp. A nonmitochondrial Ca2+ pool thus appears mainly responsible for the Ca2+ accumulation stimulated by dbcAMP and Vp in isolated hepatocytes, and cyclic AMP seems able to activate Ca2+ uptake in such a nonmitochondrial pool.
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PMID:Role of a nonmitochondrial Ca2+ pool in the synergistic stimulation by cyclic AMP and vasopressin of Ca2+ uptake in isolated rat hepatocytes. 165 13

The effect of parathyroid hormone (PTH)-like peptide PTH-related protein (PTHrP)(1-34) from a human cancer cell line on renal electrolyte transport was compared with human PTH(1-34) in a thyroparathyroidectomized anesthetized rat model. Comparing submaximal, maximal and supramaximal phosphaturic concentrations of hPTH with the same PTHrP concentrations, no significant difference could be demonstrated in the urinary excretion of calcium, magnesium, inorganic phosphate or cAMP. Even the small (30.3%) and brief (45 min) reduction in fractional water excretion with the maximal (1 nM/kg/h) hPTH concentration was approximated by PTHrP. It is concluded that the structural homology between hPTH and PTHrP allows a similar action on renal electrolyte transport, including the partial agonist effect of higher concentrations of PTH on vasopressin-induced water transport.
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PMID:Synthetic human parathyroid hormone-related protein and rat renal electrolyte transport. 166 7

Membrane preparations of cultured human retinal pigment epithelial (RPE) cells were incubated with various concentrations of [3H]arginine vasopressin (AVP) in the presence and absence of 10 microM nonradioactive AVP. Saturable, specific binding to a single site with a Kd of 6.2 nM and Bmax of 111 fmol/mg protein was detected. Vasopressin had no effect on RPE cyclic AMP levels measured by radioimmunoassay. Intracellular calcium fluxes were measured by spectrofluorometry of RPE cell suspensions preloaded with quin 2. The baseline cytosolic calcium level was 217 +/- 20 nM, and AVP caused a concentration-dependent increase in this level with a 3.5-fold maximal response at 10(-6) M and an EC50 of 120 nM. The production of inositol phosphates was measured in RPE preloaded with [3H]myoinositol, and AVP caused a concentration-dependent increase in their production with a 2.1-fold maximal response at 10(-5) M and an EC50 of 80 nM. A specific vasopressin receptor antagonist, SKF 101926, prevented the AVP-induced increase in calcium mobilization and inositol phosphate production in RPE. These data suggest that RPE cells possess V1 AVP receptors coupled to calcium mobilization and inositol phosphate metabolism.
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PMID:Human retinal pigment epithelial cells possess V1 vasopressin receptors. 166 20

The acute effects of i.v. somatostatin (250 mcg bolus followed by 250 mcg/h continuous infusion for two hours) on renal hemodynamics, renal electrolyte and water handling, and urinary excretion of catecholamines and prostaglandins, as well as on plasma concentrations of arginine vasopressin, atrial natriuretic factor, norepinephrine, epinephrine, dopamine, glucagon, and plasma renin activity were studied in seven normal subjects. Somatostatin decreased effective renal plasma flow and glomerular filtration rate, osmotic and free water clearances, urine volume, and sodium and potassium excretion, while urinary osmolality, fractional excretion of sodium, and phosphate excretion increased significantly. Plasma concentrations of arginine vasopressin, atrial natriuretic factor, norepinephrine, epinephrine, and dopamine remained unchanged, while plasma renin activity (3.0 +/- 0.25 vs 2.4 +/- 0.2 ng AngI/ml/h; p less than 0.01) and glucagon levels (40 +/- 11 vs 20 +/- 16 pg/ml; p less than 0.01) decreased. Urinary excretion of norepinephrine, epinephrine, dopamine, PGE2, and PGF2 alpha was suppressed under somatostatin. A significant positive correlation was found between urinary dopamine and sodium excretion (r = 0.7; p less than 0.001) and urinary prostaglandin E2 and glomerular filtration (r = 0.52; p less than 0.01). Without accompanying changes in plasma osmolality and vasopressin concentration significant antidiuresis occurred, suggesting a direct tubular effect of somatostatin. However, the hormone-induced changes are due mainly to the decrease in renal plasma flow. The results demonstrate that somatostatin at supraphysiological doses exerts significant effects on the kidney.
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PMID:Effect of somatostatin on kidney function and vasoactive hormone systems in health subjects. 168 Nov 32

The physiological effects of the sulfoconjugates of epinephrine, norepinephrine, and the 3-O-methylated catecholamines, metanephrine, normetanephrine, and methoxytyramine were examined with regard to their alpha 2-adrenoceptor binding properties and aggregation activity in human platelets. Sulfoconjugation of catecholamines resulted in the loss of both their competitive potency for [3H]yohimbine binding and their influence on platelet aggregation. O-Methyl substituted catecholamines showed attenuation of their alpha 2-adrenoceptor binding affinities when compared with those of the corresponding non-esterified amines. Unlike the free amine epinephrine, which stimulated platelet aggregation, the O-methylated catecholamine derivatives inhibited aggregation. Inhibition was dose-dependent and restricted to the alpha 2-adrenoceptor mediated aggregation response stimulated by epinephrine (1 microM) or potentiated by subthreshold concentrations of epinephrine (30-300 nM) in the presence of subaggregatory doses of vasopressin (10-30 nM). Collagen- and ADP-induced platelet aggregation was not affected. The hydrophilic beta-antagonist CGP 12177 displayed no effects. However, high concentrations (0.1 mM) of both isomers of the strongly lipophilic beta-adrenoceptor antagonist propranolol inhibited the actions of all aggregators by stabilizing the membrane. Such a nonspecific membrane interaction of the methylated catecholamines could be excluded because of their low lipid solubility calculated in a n-octanol-phosphate buffer system at pH 7.4. We suggest therefore that methylated catecholamines are biological alpha 2-adrenoceptor antagonists acting on alpha 2-adrenoceptor stimulated reactions of human platelets. Whether this receptor antagonism is relevant to other human tissues needs clarification. Sulfated catecholamines, however, are wholly ineffective at this receptor site and may constitute a pathway to control the concentration of the active free catecholamines.
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PMID:O-Methylated and sulfoconjugated catecholamines: differential activities at human platelet alpha 2-adrenoceptors. 168 67


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