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 presence of several naturally occurring amino acids in the serosal bath of toad urinary bladder significantly alters the hydrosmotic response of this tissue to vasopressin. We found that histidine, glutamate, and lysine increase vasopressin-stimulated water flow by 75%, 60%, and 43%, respectively. In contrast, alanine did not alter vasopressin-stimulated water flow, whereas glutamine decreased it by 25%. The effect of each amino acid represents intracellular events because their effects on theophylline-stimulated water flow were similar to those found with vasopressin. However, the site of action of amino acids varied, with some operating at steps before and others at steps after cyclic AMP generation. The fact that the metabolically inactive D-histidine and D-glutamate are as effective as their metabolically active L-counterparts suggests that the action of amino acids depends upon some physicochemical properties of their molecules. The ability of amino acids to influence the hydrosmotic effects of vasopressin was shown to be independent of prostaglandin generation, ionic composition, and molecular charge. In the case of histidine, we were able to obtain some understanding of the mechanism responsible for its action. We first showed that the effect of histidine does not depend upon its metabolism. In addition to D-histidine being as effective as the metabolically active L-histidine, we also showed that histidine is effective when its metabolism is abolished by low ambient temperature and also when its incorporation into proteins was prevented by cycloheximide. These findings suggest that histidine operates through some physicochemical property localized on its molecule. We were able to show that this property resides on the imidazole part of histidine. Imidazole, similar to histidine, increases vasopressin-stimulated water flow. Methylation of histidine on the imidazole ring completely abolished its effectiveness in increasing vasopressin-stimulated water flow. In contrast, methylation of histidine at the side chain increased vasopressin action similar to that found for histidine. We provide evidence that the physicochemical property of the imidazole ring of histidine is that of chelating Zn++ intracellularly, and that the intracellular site of action of histidine is closely linked to microtubules formation and/or action.
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PMID:Importance of amino acids on vasopressin-stimulated water flow. 286 87

The effect of (R,S)-(3,4-dihydro 6,7-dimethoxy-isoquinoline-1-yl)-2-phenyl- N,N-di-[2-(2,3,4-trimethoxyphenyl)ethyl]-acetamide (LOE 908), a cation channel blocker in HL-60 promyeloblasts, was studied in the A7r5 smooth muscle cell line from rat thoracic aorta, using the whole-cell patch-clamp technique. At a holding potential of -60 mV, application of vasopressin induced a nonselective cation conductance in voltage-clamped A7r5 cells. The current-voltage relation was linear, and currents reversed close to 0 mV regardless of the chloride gradient. The activation of the nonselective cation conductance by vasopressin was not affected by dialysing cells with Ca(2+)-free internal solution. LOE 908 blocked this current in a concentration-dependent manner with an IC50 of 560 nM, whereas dihydropyridine-sensitive Ba2+ current through voltage-dependent Ca2+ channels was blocked with an IC50 of 28 microM. Another organic blocker of receptor-mediated Ca2+ entry, 1-beta-[3-(4-methoxyphenyl)-propoxy]-4-methoxyphenethyl-1H-imidazole hydrochloride (SK&F 96365), blocked both, the vasopressin-induced nonselective conductance and the voltage-activated Ba2+ current with similar IC50 values of 13 microM and 8 microM, respectively. The rank order of potency of inorganic blockers on the vasopressin-induced inward current was Gd3+ > La3+ > Cd2+. Vasopressin-induced non-selective cation current was also observed in pertussis toxin-pretreated A7r5 cells but was completely abolished after infusion of the GDP analogue, guanosine 5'-O-[3-thio]diphosphate, from the patch pipette. Furthermore, vasopressin induced a transient outward current, suggesting a Ca(2+)-activated K(+)-current, which overlapped with the nonselective cation conductance.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The isoquinoline derivative LOE 908 selectively blocks vasopressin-activated nonselective cation currents in A7r5 aortic smooth muscle cells. 751 40

The inhibition of agonist-stimulated divalent cation inflow in hepatocytes by Gd3+ and compound SK&F 96365 (1-[beta-[3-(4-methoxyphenyl)propoxy]-4-methoxyphenethyl]-1H-imidazole hydrochloride) was investigated. Gd3+ and SK&F 96365 inhibited Ca2+ and Mn2+ inflow stimulated by vasopressin, angiotensin II or phenylephrine. The concentrations of Gd3+ and SK&F 96365 which gave half-maximal inhibition of vasopressin-stimulated Ca2+ inflow were 2 x 10(-7) M and 16 x 10(-6) M, respectively. The action of Gd3+ on vasopressin-stimulated Ca2+ inflow was rapid (less than 10 s in onset) and reversible. Gd3+ had no effect on Mn2+ inflow in the absence of an agonist and no effect on the ability of vasopressin to release Ca2+ from intracellular stores. SK&F 96365 inhibited Mn2+ inflow in the absence of agonists and vasopressin-induced release of Ca2+ from intracellular stores, but at approximately a 5-fold higher concentration than that which inhibited vasopressin-stimulated divalent cation inflow. It is concluded that Gd3+ and SK&F 96365 (at concentrations below 20 microM) inhibit, in a selective manner, divalent cation movement through the putative cation channel of the hepatocyte receptor-activated Ca2+ inflow system. Gd3+ appears to be the most potent inhibitor of this Ca2+ inflow system so far described.
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PMID:Characterisation of the inhibition of the hepatocyte receptor-activated Ca2+ inflow system by gadolinium and SK&F 96365. 803 6

Experiments were conducted to characterize the thapsigargin-stimulated plasma membrane Ca2+ inflow pathway in hepatocytes. Ca2+ inflow was estimated by measurement of the initial rate of activation of glycogen phosphorylase a following the addition of Ca2+ to cells previously incubated in the absence of added Ca2+. Pretreatment of hepatocytes with thapsigargin caused a substantial stimulation of the rate of Ca2+ activation of glycogen phosphorylase a. This was interpreted to reflect a stimulation of plasma membrane Ca2+ inflow. The effect of thapsigargin on plasma membrane Ca2+ inflow was approximately 65% of the magnitude of the effect caused by vasopressin. When thapsigargin and vasopressin were combined as a stimulus, the degree of stimulation was similar to that caused by vasopressin alone. The thapsigargin-induced stimulation of the rate of Ca2+ activation of glycogen phosphorylase a was inhibited in a concentration-dependent manner by both Zn2+ and 1-(beta-[3-(4-methoxyphenyl)propoxy]-4-methoxyphenethyl)-1H-imidazole hydrochloride (SK&F 96365). The concentration of each agent required for half-maximal inhibition was approximately 20 microM. It is concluded from: (i) the apparent lack of additivity in the responses of thapsigargin and vasopressin, and (ii) the sensitivity to inhibitors, that the Ca2+ inflow pathway in hepatocytes stimulated by thapsigargin is likely to be similar to that which is activated by vasopressin.
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PMID:Evidence that the Ca2+ inflow pathway in hepatocytes stimulated by thapsigargin is similar to that activated by vasopressin. 851 98

Vasopressin ([Arg(8)]vasopressin)-induced contraction was characterized using receptor agonists and antagonists for vasopressin and channel blockers in the rat basilar artery ring preparations. Vasopressin induced rhythmic contractions superimposed on a contraction in endothelium-intact preparations but not in denuded ones. Endothelium removal shifted the concentration-response curve for vasopressin leftward and upward. In endothelium-denuded preparations, vasopressin V(1) receptor antagonist shifted the concentration-response curve for vasopressin downward and rightward. Vasopressin V(1) receptor agonist caused contraction but V(2) receptor agonist did not. The contractile response to vasopressin was partly inhibited by nifedipine, SK&F 96365 (1-[beta-[3-(4-methoxyphenyl)propoxy]-4-methoxyphenethyl]-1H-imidazole) and niflumic acid. In the absence of extracellular Ca(2+), vasopressin produced a transient contraction. Charybdotoxin produced an upward and leftward shift of the concentration-response curve for vasopressin. These results suggest that vasopressin elicits contraction due to Ca(2+) influx through voltage-dependent and receptor-operated Ca(2+) channels and to Ca(2+) release from Ca(2+) stores by activating vasopressin V(1) receptors in the rat basilar artery.
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PMID:Vasopressin-induced contraction in the rat basilar artery in vitro. 1128 20

Store-operated Ca(2+) channels in liver cells have been shown previously to exhibit a high selectivity for Ca(2+) and to have properties indistinguishable from those of Ca(2+)-release-activated Ca(2+) (CRAC) channels in mast cells and lymphocytes [Rychkov, Brereton, Harland and Barritt (2001) Hepatology 33, 938-947]. The role of CRAC channels in the maintenance of hormone-induced oscillations in the cytoplasmic free Ca(2+) concentration ([Ca(2+)](cyt)) in isolated rat hepatocytes was investigated using several inhibitors of CRAC channels. 2-Aminoethyl diphenylborate (2-APB; 75 microM), Gd(3+) (1 microM) and 1-[beta-[3-(4-methoxyphenyl)propoxy]-4-methoxyphenethyl]-1H-imidazole hydrochloride (SK&F 96365; 50 microM) each inhibited vasopressin- and adrenaline (epinephrine)-induced Ca(2+) oscillations (measured using fura-2). The characteristics of this inhibition were similar to those of inhibition caused by decreasing the extracellular Ca(2+) concentration to zero by addition of EGTA. The effect of 2-APB was reversible. In contrast, LOE-908 [( R, S )-(3,4-dihydro-6,7-dimethoxy-isochinolin-1-yl)-2-phenyl- N, N -di[2-(2,3,4-trimethoxyphenyl)ethyl]acetamide mesylate] (30 microM), used commonly to block Ca(2+) inflow through intracellular-messenger-activated, non-selective cation channels, did not inhibit the Ca(2+) oscillations. In the absence of added extracellular Ca(2+), 2-APB, Gd(3+) and SK&F 96365 did not alter the kinetics of the increase in [Ca(2+)](cyt) induced by a concentration of adrenaline or vasopressin that induces continuous Ca(2+) oscillations at the physiological extracellular Ca(2+) concentration. Ca(2+) inflow through non-selective cation channels activated by maitotoxin could not restore Ca(2+) oscillations in cells treated with 2-APB to block Ca(2+) inflow through CRAC channels. Evidence for the specificity of the pharmacological agents for inhibition of CRAC channels under the conditions of the present experiments with hepatocytes is discussed. It is concluded that Ca(2+) inflow through CRAC channels is required for the maintenance of hormone-induced Ca(2+) oscillations in isolated hepatocytes.
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PMID:Evidence that Ca2+-release-activated Ca2+ channels in rat hepatocytes are required for the maintenance of hormone-induced Ca2+ oscillations. 1246 Jan 23

Neurotensin (NT) stimulates Ca2+ release and Ca2+ influx in many cells. Its contractile effects in smooth muscle are inhibited by removal of Ca2+ and by Ca2+ channel blockers (CCBs). To better understand NT signaling in prostate cancer PC3 cells, blockers of voltage-gated and store-operated Ca2+ channels (VGCC and SOCC) were tested for effects on NT-binding and signaling. Eight chemical types of agents, including VGCC-blocker nifedipine and SOCC-blocker SKF-96365 (1-[beta-[3-(4-methoxyphenyl)-propoxy]-4-methoxyphenyl]-1H-imidazole), enhanced cellular NT binding up to 3-fold, while inhibiting (by congruent with 70%) NT-induced inositol phosphate (IP) formation. The ability to enhance NT binding correlated with the ability to inhibit NT-induced IP formation, and both effects were relatively specific for NT. Although cellular binding for beta2-adrenergic, V1a-vasopressin, and epidermal growth factor receptors was not enhanced by these drugs, bombesin receptor binding was increased approximately equal to 19% and bombesin-induced IP formation was inhibited approximately equal to 15%. One difference was that the effect on NT binding was Ca2+-independent, whereas the effect on IP formation was Ca2+-dependent (in part). The Ca2+-dependent part of the IP response seemed to involve SOCC-mediated Ca2+ influx to activate phospholipase C (PLC)delta, while the Ca2+-independent part probably involved PLCbeta. Photoaffinity labeling of the NT receptor NTR1 was enhanced in CCB-treated cells. NTR1 affinity was increased but NTR1 number and internalization were unchanged. Since CCBs did not alter NT binding to isolated cell membranes, the effects in live cells were indirect. These results suggest that CCBs exert two effects: 1) they inhibit NT-induced IP formation, perhaps by preventing Ca2+ influx-dependent activation of PLCdelta; and 2) they enhance NTR1 affinity by an unexplained Ca2+-independent mechanism.
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PMID:Ca2+ channel blockers enhance neurotensin (NT) binding and inhibit NT-induced inositol phosphate formation in prostate cancer PC3 cells. 1457 Aug 23

Adrenomedullin 2/intermedin (AM2/IMD) is a novel member of the calcitonin/calcitonin gene-related peptide (CGRP) peptide family. AM2/IMD has a vasodilator action, and antidiuretic and antinatriuretic effects in mice. The aim of the present study is to clarify immunolocalization of AM2/IMD in human hypothalamus, heart and kidney obtained at autopsy. Immunocytochemistry showed AM2/IMD-immunoreactive cell bodies in the paraventricular and supraoptic nuclei of human hypothalamus. Both parvocellular and magnocellular cells in the paravetricular nucleus are immunostained with AM2/IMD. Immunostaining of serial sections showed co-localization of AM2/IMD-like immunoreactivity and vasopressin in the paraventricular nucleus. Myocardial cells of the heart and renal tubular cells were positively immunostained with AM2/IMD, whereas neither renal glomeruli nor vasculature in the heart and kidney were immunostained. Reverse-transcriptase polymerase chain reaction confirmed expression of AM2/IMD mRNA in the brain, pituitary, heart and kidney. The present study has shown the wide expression of AM2/IMD in human hypothalamus, heart and kidney, raising the possibility that this novel peptide may be related to the central and peripheral regulation of the circulation and water-electrolyte metabolism.
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PMID:Immunocytochemical localization of adrenomedullin 2/intermedin-like immunoreactivity in human hypothalamus, heart and kidney. 1635 54

Receptors for benzodiazepines have recently been found in the brain but the natural ligand which can occupy these receptors is unknown. In a rat vascular preparation diazepam and chloridiazepoxide were found to inhibit pressor responses to noradrenaline and angiotensin but not those to potassium and vasopressin with IC(50) concentrations similar to those reported for displacement of [(3)H]diazepam from brain receptors. Imidazole, an inhibitor of thromboxane A(2) synthesis had similar actions to the benzodiazepines. Interactions between imidazole and the benzodiazepines suggested that the latter may be competitive antagonists of thromboxane A(2). The possibility that thromboxane A(2) may be the natural ligand is supported by recent evidence that brain tissue contains high levels of this substance.
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PMID:Thromboxane A(2) as a possible natural ligand for benzodiazepine receptors. 1960 84