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)

Platelets lose their ability to aggregate when deprived of divalent cations. This usually was studied by incubating human citrated platelet-rich plasma with EDTA or EGTA and then adding enough CaCl2 to combine with the chelating agent. Incubation for 5-7 min at 37 degrees C caused irreversible loss of the platelets' ability to adhere to glass and to aggregate with ADP, epinephrine, A23187, vasopressin, or serotonin or upon rewarming after chilling and markedly reduced aggregation with collagen or thrombin. Control samples incubated with saline, CaEDTA, or CaEGTA were not inhibited. Untreated platelets washed and incubated in solutions treated with resins that remove divalent cations lost their ability to aggregate in 30 min. More than about 0.26 mM Mg2+ partially protected the platelets. Unlike aggregation, ADP-induced shape change, clot retraction caused by thrombin or ADP plus reptilase, and thrombin-induced 14C-serotonin release were not inhibited after incubation. Aggregability was not restored by prolonged incubation with CaCl2, adding normal plasma, or washing the platelets. Its loss was temperature and pH dependent, occurring in 2 min at 43 degrees C but not in 7 min at 30 degrees C, and at pH 7.8 but much less at pH 7.2. The defect was not associated with an increase in platelet cyclic AMP, a decrease in metabolic ATP, or the presence of free ADP.
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PMID:Nonreversible loss of platelet aggregability induced by calcium deprivation. 67 68

Cadmium ion (Cd++) significantly increased potential difference (PD) and short-circuit current (SCC) across isolated frog skin when added to the outside Ringer's solution at 10(-4), 10(-3) and 5 X 10(-3) M concentration. Resistance was reduced by 10(-4) 7 cd++ but not significantly changed by the higher concentrations. When SCC was first stimulated by vasopressin, 10(-4) and 10(-3) M Cd++ produced additive stimulation which was reversible by washing with Cd++-free Ringer's. If SCC was first stimulated by Cd++, further stimulation by vasopressin was additive with 10(-4)M Cd++ but dompletely inhibited by 10(-3)M Cd++. Elevating the calcium ion (Ca++) concentration of the outer Ringer's from 10(-3) M to 5 X 10(-3)M or 10(-2)M prior to Cd++ treatment did not reduce the magnitude of SCC stimulation by Cd++. Removal of Ca++ from the outside Ringer's with 2 X 10%-3)M EDTA increased SCC as predicted. Subsequent addition of 5 X 10(-3) M Cd++ drastically reduced SCC below control levels while equimolar concentrations of Cd++ and EDTA reduced SCC only to control levels. These results suggest that Cd++ interacts with the components of the apical plasma membranes of epithelial cells which are associated with the stimulation of SCC by vasopressin and Ca++ removal and may be a useful probe for elucidating these components.
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PMID:Effects of Cd++ on short-circuit current across epithelial membranes. I. Interactions with Ca++ and vasopressin on frog skin. 81 28

The reaction products of plasma enzyme degradation of TRH were identified by thin layer chromatography. The enzyme in normal rat plasma yields proline and pGlu-His as major reaction products. High concentrations of proline decrease peptide cleavage, resulting in greater amounts of acid TRH. The apparent Km of the enzyme is 4.1 X 10(-6) M. LHRH and neurotensin are competitive inhibitors with Ki of 5 X 10(-6) M and 1.5 X 10(-5) M, respectively. Somatostatin, MIF, oxytocin, arg-vasopressin, arg-vasotocin, neurophysin II and glucagon do not compete; and pGlu-His-Pro-OH, Glu-His-Pro-OH, pGlu-His, His-Pro-NH2, and Pro-NH2 do not affect enzyme activity. These data suggest that the substrated requires pGlu and a terminal or internal amide to complex with the enzyme. The enzyme is markedly inhibited by Cu++, Bal, benzamadine, p-(chloromercuri)-benzoic acid, moderately affected by EDTA and puromycin, and unaffected by mercaptoethanol. TSH does not affect enzyme activity while LH inhibits it moderately at high concentrations (300-600 pg/ml).
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PMID:Characteristics of the plasma TRH-degrading enzyme. 81 19

Protein kinase C (PKC) acts in synergy with Ca2+ mobilization for the activation of platelets. Three different PKC subtypes that specifically react with antibodies to alpha- beta- and zeta-PKC have been detected in human platelets. We have compared the subcellular redistribution of these isoforms in platelets after exposure to the tumour-promoting phorbol ester phorbol 12-myristate 13-acetate (PMA) and to two physiological agonists, thrombin and vasopressin. In the presence of PMA, beta-PKC is most rapidly translocated to membranes, followed by zeta-PKC and alpha-PKC [membrane contents of 39 +/- 6, 31 +/- 4 and 24 +/- 4% (means +/- S.E.M.) respectively after 2 min incubation]. In contrast, both thrombin and vasopressin induced a biphasic translocation of PKC isoforms. For both agonists, the first phase of translocation occurred within 1 min and was identical for the three isoforms. However, during the second phase, the translocation of zeta-PKC by thrombin and vasopressin differed [membrane contents (mean +/- S.E.M.) of 24 +/- 3 and 46 +/- 4% respectively after 10 min]. These results suggest a differential activation of zeta-PKC by vasopressin and thrombin. PMA-induced translocation of alpha-PKC was decreased from 278 +/- 27 to 198 +/- 24 (mean +/- S.E.M., P = 0.02; percentage increase over control value) in the presence of 1 mM-EDTA, whereas chelation of intracellular Ca2+ by Quin2-AM does not influence this response. These results suggest that the PMA-induced translocation of alpha-PKC depends on the presence of 1 mM concentration of extracellular Ca2+. In addition, the chelation of either extracellular or intracellular Ca2+ inhibited both vasopressin- and thrombin-induced translocation of all three isoforms, suggesting that Ca2+ is an important requirement for the translocation of alpha-, beta- and zeta-PKC by physiological agonists. In conclusion, the translocation of PKC varies between different isoforms and between different agonists.
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PMID:Effect of tumour-promoting phorbol ester, thrombin and vasopressin on translocation of three distinct protein kinase C isoforms in human platelets and regulation by calcium. 147 2

A five-year-old girl with known sickle cell disease presented with severe hyponatremia and findings compatible with syndrome of inappropriate secretion of antidiuretic hormone (SIADH). She was found to have lead levels in the Class III category. By exclusion, we postulated that the SIADH was in some way related to the high lead levels, since this was the only abnormality the patient exhibited. The toxic lead levels and the elevated vasopressin levels rapidly responded to dimercaprol and calcium EDTA chelation therapy.
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PMID:Elevated lead levels in a patient with sickle cell disease and inappropriate secretion of antidiuretic hormone. 160 8

The proteolytic conversion of oxytocin and Arg8-vasopressin by purified rat thymocytes was studied at 37 degrees C and physiological pH 7.4. The formed peptide fragments were isolated by high performance liquid chromatography and characterized by amino acid analysis. When oxytocin was incubated with rat thymocytes, oxytocin 1-8 and oxytocin 1-7 were isolated. In contrast, only Arg8-vasopressin 1-8 was found when Arg8-vasopressin was incubated with thymocytes. The formation of oxytocin 1-8, oxytocin 1-7 and Arg8-vasopressin 1-8 was prevented partially by 10(-3) M phenylmethylsulfonyl fluoride and iodoacetamide, and abolished by 0.5 x 10(-3) M Zn2+ and Hg2+ ions and 10(-3) M o-phenanthroline, but not by 10(-5) M leupeptin, lima bean trypsin inhibitor, trasylol, captopril and phosphoramidon. 0.5 x 10(-3) M EDTA was without effect on the formation of oxytocin 1-8 and Arg8-vasopressin 1-8 but increased by about 30% the formation of oxytocin 1-7. The results suggest that proteases capable of metabolizing oxytocin and Arg8-vasopressin are localized in the thymocyte surface membrane. Since oxytocin and vasopressin are synthetized by thymic epithelial cells and exert several actions on thymocytes, these proteases may play a physiological role in the inactivation of neurohypophyseal peptides at the thymocyte level.
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PMID:Proteolytic conversion of neurohypophyseal peptides by rat thymocytes: involvement of endopeptidases. 164 Oct 73

Dexamethasone 21-acetate (DMS 21-A) time- and dose-dependently suppressed bradykinin-stimulated prostacyclin synthesis in porcine aortic endothelial cells. The suppression was more prominent in the presence of pertussis toxin, which by itself could enhance bradykinin-induced prostacyclin synthesis. The DMS 21-A treatment diminished prostacyclin synthesis also in response to vasopressin. In contrast, it did not affect prostacyclin synthesis in response to arachidonic acid or A23187. Melittin-induced prostacyclin synthesis was reduced only at low doses (1-7 x 10(-7) M). The suppression of bradykinin-induced prostacyclin synthesis by DMS 21-A was completely blocked by cycloheximide. DMS 21-A had no effect on the cellular level of lipocortin I protein, but increased the anti-phospholipase A2 activity in EDTA extracts of the cells. These results suggest that the DMS 21-A treatment induces phospholipase A2 inhibitor protein(s) other than lipocortin I and reduces prostacyclin production in response to limited stimuli.
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PMID:Glucocorticoid treatment reduces prostacyclin synthesis in response to limited stimuli. 182 73

The vasoconstrictor responses induced by noradrenaline (NA), adrenaline (AD), serotonin (ST) and vasopressin (VP) on the anterior mesenteric artery of the rat and its branches, were maintained, although somewhat reduced when perfused with a Ca free solution that depletes extracellular Ca. The vasoconstrictor responses were abolished when Lanthanum, EDTA, Verapamil or Nifedipine were added to the Ca free solution. These drugs are known to displace plasmalemmal bound Ca that triggers vasoconstriction when the agonists attach to the receptors thus blocking the vasoconstrictor responses. When the mesenteric arteries were perfused with a Ca containing solution, to block the vasoconstriction induced by the agonists the concentration of La3+, EDTA, Verapamil and Nifedipine must be raised. Thus these drugs appear to compete with extracellular ionic Ca for the membranal sites involved in the activity of the agonists. K induced vasoconstriction was abolished when extracellular Ca was depleted by a Ca free solution and with lower concentrations of the anticalcic drug than those used to cancel the effect of the agonists. Ca appears to be attached to voltage operated channels less firmly than to receptor operated channels. NA, AD, ST and VP showed different sensitivity to the blocking effect of the various anticalcic drugs. This is probably explained by small differences in the structure of the Ca channels operated by the agonists.
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PMID:Organic and inorganic calcium blockers on voltage and receptor operated channels of resistance arteries of the rat. 257 39

The binding of 3H-labelled [8-arginine]vasopressin to human platelets or crude platelet membranes was examined. Both preparations specifically bound [8-arginine]vasopressin. The binding increased linearly with protein concentration, it was temperature- and time-dependent, saturable and could be reversed to a large extent by EDTA (10 mM). In this latter case, addition of an excess of MgCl2 (20 mM) restored the initial level of binding. Intact platelets and membranes derived from these platelets presented a single population of binding sites with a dissociation constant (Kd) of 1.3 +/- 0.2 and 1.8 +/- 0.3 nM and a maximal binding capacity of 142 +/- 48 and 270 +/- 17 fmol/mg of protein, respectively. The Kd values of various analogues correlated well with those determined on rat liver membrane V1 vasopressin receptors but not with those determined on rat kidney membrane V2 receptors.
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PMID:Nature and properties of human platelet vasopressin receptors. 301 Sep 40

Arginine-vasopressin (AVP) caused a marked shape change reaction and rise in [Ca2+]i in human blood platelets only when the extracellular buffer contained Mg2+ or Ca2+. At physiological concentrations of the cations the potency of AVP was higher in the presence of Mg2+ than of Ca2+. The amplitude of the shape change reaction was also greater with Mg2+ than with Ca2+, although the [Ca2+]i-rise was slightly more marked with extracellular Ca2+. The concentration of Mg2+ at which AVP showed half of its maximal effects was below the physiological plasma level of the cation, whereas the corresponding value for Ca2+ was higher. Addition of Ca2+ to the Mg2+ containing medium did not further enhance the action of AVP on platelet shape. In platelet-rich plasma the potency and efficacy of AVP in causing a shape change were similar in the presence and absence of EGTA, whereas with EDTA in the medium AVP had no effect. In conclusion, Mg2+ has an essential physiological role in AVP-induced platelet activation, which is brought about partly by release of intracellular calcium and partly by some other intracellular mechanism.
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PMID:Vasopressin-induced activation of human blood platelets: prominent role of Mg2+. 315 25


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