Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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 rate of vanadate-sensitive 22Na+ uptake by isolated liver membrane vesicles, reflecting transport by Na+/K(+)-ATPase, was measured to study the role played by phospholipase C and protein kinase C in the regulation of this process by vasopressin. Na+ uptake was enhanced 2-3-fold by 100 nM [Arg8]vasopressin and the hormone effect was mimicked by 0.1 microM inositol 1,4,5-trisphosphate as well as by 1.0 microM myo-inositol. The stimulation by vasopressin was potentiated by phosphatidylinositol-specific phospholipase C from Bacillus thuringiensis (5-10 mU/ml). No effect of the bacterial enzyme was observed in the absence of the hormone. Phorbol myristate acetate (0.5-1 microM) suppressed the stimulation by vasopressin but had no effect in the absence of the hormone. High concentrations of bacterial phosphatidylinositol-specific phospholipase C (50-100 mU/ml) also antagonized the hormone stimulation. Staurosporine (50-100 nM) prevented the antagonistic effect of bacterial phospholipase C (50 mU/ml) and EGTA (1 mM) partially protected the hormonal stimulation in the presence of phorbol myristate acetate. Our results suggest that the stimulatory effect of vasopressin on Na+ transport is mediated by phospholipase C and products derived from the inositol moiety of membrane phospholipids. Membrane-associated protein kinase C appears to be at least partially responsible for the desensitization to stimulation by vasopressin.
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PMID:Vasopressin stimulation of vanadate-sensitive Na+ transport by liver plasma membrane vesicles. Evidence for regulation via phospholipase C and protein kinase C activities. 139 Aug 61

The monohydroxy bile acid taurolithocholate (TLC) causes a rapid and transient increase in free cytosolic Ca2+ concentration ([Ca2+]i) in suspensions of rat hepatocytes similar to that elicited by the InsP3-dependent hormone vasopressin. The effect of the bile acid is due to a mobilization of Ca2+, independent of InsP3, from the endoplasmic reticulum (ER). Short-term preincubation of cells with the phorbol ester 4 beta-phorbol 12 beta-myristate 13 alpha-acetate (PMA), which activates protein kinase C (PKC), blocked the increase in [Ca2+]i induced by TLC, but did not alter that mediated by vasopressin. We obtained the following results, indicating that the effect of PMA is mediated by the activation of PKC. (1) Phorbol esters were effective over a concentration range where they activate PKC (IC50 = 0.5 nM); (2) phorbol esters that do not activate PKC did not inhibit the effects of TLC; (3) the permeant analogue oleoylacetylglycerol mimicked the inhibitory effect of PMA; (4) lastly, the inhibition of the TLC-induced Ca2+ mobilization by phorbol esters was partially prevented by preincubating the cells with the PKC inhibitors H7 and AMG-C16. Preincubating hepatocytes with PMA had no effect on the cell uptake of labelled TLC, indicating that the phorbol ester does not interfere with the transport system responsible for the accumulation of bile acids. In saponin-treated liver cells, PMA added before or after permeabilization failed to abolish TLC-induced Ca2+ release from the ER. The possibility is discussed that PMA, via PKC activation, may alter the intracellular binding or the transfer of bile acids in the liver.
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PMID:Taurolithocholate-induced Ca2+ release is inhibited by phorbol esters in isolated hepatocytes. 144 48

Many hormones and drugs exert their effects on cells by increasing cytosolic Ca2+ (Cai2+) and activating protein kinase C (PKC). Each of these actions results in cholestasis in the isolated perfused rat liver, but the responsible mechanisms are unclear. We used isolated rat hepatocyte couplets to observe the direct effects of increased Cai2+ and PKC activation on permeability of the hepatocyte tight junction and canalicular volume, two possible determinants of hepatocyte bile secretion. Couplets were stimulated with the Ca2+ agonist vasopressin (10(-8) M) in the absence and presence of the Ca2+ influx antagonist Ni2+ (5 x 10(-3) M) or with the PKC activator phorbol dibutyrate (10(-6) M). Cai2+ was determined by ratio microspectrofluorometry of indo-1, permeability of the couplet tight junctions was assessed by exclusion of horseradish peroxidase from the canalicular space, and changes in canalicular volume over time were measured directly by optical planimetry. Canalicular volume increased by 1.6 +/- 2.5%/min (mean +/- SD) under basal conditions. In response to vasopressin, there was a rapid 15-fold increase in Cai2+, followed first by an increase in paracellular permeability, then by canalicular collapse (15.9 +/- 5.9%/min). Pretreatment with Ni2+ markedly decreased the vasopressin-induced increase in Cai2+ and abolished both the increase in paracellular permeability and the canalicular collapse. Phorbol dibutyrate also increased paracellular permeability but resulted in neither increased Cai2+ nor canalicular collapse. The PKC inhibitor H-7 reversed the effects of both vasopressin and phorbol dibutyrate on tight junction permeability. Bile secretory pressure, measured in isolated perfused rat liver preparations, was acutely increased by vasopressin, but the increase was augmented rather than inhibited by Ni2+.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Hormonal regulation of paracellular permeability in isolated rat hepatocyte couplets. 161 38

Treatment of quiescent Swiss 3T3 cells with the mitogenic peptides bombesin, vasopressin, endothelin/vasoactive intestinal contractor (VIC), and bradykinin strikingly increased the initial rate of tyrosine phosphorylation measured in anti-phosphotyrosine immunoprecipitates of a major band of Mr 115,000 (p115) and two minor components of Mr 90,000 and 75,000. Neuropeptides increased the labeling of p115 within seconds and with great potency; half-maximum concentrations were 0.1, 0.2 and 0.3 nM for bombesin, vasopressin, and VIC, respectively. Immunoblotting and peptide mapping showed that the p115 band phosphorylated in anti-phosphotyrosine immunoprecipitates is identical to a major Mr 115,000 substrate for neuropeptide-stimulated tyrosine phosphorylation in intact Swiss 3T3 cells. Furthermore, bombesin, vasopressin, and VIC markedly increased the rate of phosphorylation of Raytide, a broad specificity tyrosine kinase peptide substrate, by decreasing (8 +/- 1.3-fold) the apparent Km of the kinase for the substrate. Phorbol 12,13-dibutyrate and the Ca2+ ionophore A23187 had a weaker effect on tyrosine protein kinase activity in immune complexes compared with bombesin. Furthermore, down-regulation of protein kinase C blocked the small effect of phorbol esters but did not impair bombesin-stimulated tyrosine kinase activity. These results provide direct evidence for neuropeptide activation of a tyrosine kinase in cell-free preparations and identify a novel event in the action of this class of growth factors in Swiss 3T3 cells.
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PMID:Stimulation of tyrosine kinase activity in anti-phosphotyrosine immune complexes of Swiss 3T3 cell lysates occurs rapidly after addition of bombesin, vasopressin, and endothelin to intact cells. 172 Oct 65

The Ca2(+)-mobilizing hormone angiotensin II (AII) dose-dependently inhibited the K(+)-induced sustained increase of cytoplasmic Ca2+ concentration in adrenal glomerulosa cells and caused a rapid decrease of cytoplasmic Ca2+ when added to cells already stimulated with K+. These effects of AII on the K(+)-induced Ca2+ signal were mimicked, although less effectively, by other Ca2(+)-mobilizing agonists such as [Arg8]vasopressin (AVP) and thapsigargin. Phorbol esters did not show such effects, nor did corticotropin (ACTH), a secretagogue acting via cyclic AMP. The K(+)-stimulated initial 45Ca2+ uptake, a measure of Ca2+ entry into glomerulosa cells, was also prevented by AII pretreatment, and was inhibited by AVP, but not by ACTH. The stimulatory effect of K+ on aldosterone production, however, was not inhibited by AII, and the AII-induced aldosterone production was further increased by increasing K+. These data indicate that AII is able to inhibit static increases in cytoplasmic Ca2+ by inhibiting Ca2+ entry through voltage-sensitive Ca2+ channels and, possibly, by activating Ca2+ extrusion from the cells. It is also concluded that the Ca2+ signal evoked by AII is very efficient in stimulating hormone secretion, and the secretory response of the cells becomes more sensitive to any further increase of Ca2+ entry through voltage-sensitive Ca2+ channels.
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PMID:Angiotensin II inhibits K(+)-induced Ca2+ signal generation in rat adrenal glomerulosa cells. 184 39

We found that glucagon stimulated membrane protein kinase C (PKC) activity and phosphatidylcholine hydrolysis in 24 h-cultured rat hepatocytes. Phorbol myristate acetate, 8-bromo cyclic AMP, vasopressin, noradrenaline and the Ca2+ ionophore A23187 also stimulated membrane PKC activity. However, only vasopressin and noradrenaline stimulated inositol phosphate accumulation, whereas all agonists stimulated the rate of release of water-soluble choline metabolites into the medium. Choline, and to a much lesser extent phosphocholine, were released, suggesting predominantly phospholipase D activation. This was supported by the finding that the accumulation of phosphatidate and diacylglycerol was enhanced by the agents in [3H]myristate-labelled hepatocytes, as was [32P]phosphatidylethanol formation. Since the time courses for the release of choline into the medium and the accumulation of phosphatidate and diacylglycerol caused by vasopressin and glucagon were similar, the more rapid activation of PKC by vasopressin probably reflects diacylglycerol formation from phosphoinositide breakdown. The inability of glucagon to stimulate inositol phosphate production was not due to the prolonged culture, since similar results were obtained in 4 h cultures. We conclude that the stimulation of membrane PKC activity by glucagon correlates with accumulation of diacylglycerol and phosphatidate derived from the hydrolysis of phosphatidylcholine.
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PMID:Activation of membrane protein kinase C by glucagon and Ca(2+)-mobilizing hormones in cultured rat hepatocytes. Role of phosphatidylinositol and phosphatidylcholine hydrolysis. 185 65

Vasopressor hormones alter efflux of glutathione (GSH) and increase permeability of tight junctions in perfused rat liver. Infusions of 10 nM angiotensin II, 10 microM phenylephrine, and 10 nM vasopressin significantly increased efflux of GSH into perfusate by 32-41% and decreased biliary efflux by 31-57%. Direct modulation of protein kinase C (PKC) activity by 600 nM phorbol 12,13-dibutyrate (PDB), 5 microM 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), 5 microM sphingosine, or 10 nM staurosporine altered the pattern of efflux of GSH but not biliary oxidized glutathione disulfide (GSSG)-GSH ratios. Phorbol dibutyrate mimicked the vasopressor-mediated effects, increasing perfusate efflux by 31% and decreasing biliary efflux by 45%. Inhibitors of PKC caused qualitatively opposite responses, changing perfusate GSH by -37 to 18% and increasing biliary efflux by 22-161%. Whereas vasopressin increased penetration of [14C]sucrose into bile, modulation of PKC activity by PDB and H-7 did not affect the permeability of tight junctions to [14C]sucrose. Although pretreatment with H-7 blocked vasopressin-mediated changes in efflux of GSH, it did not prevent the increase in [14C]sucrose penetrance. We conclude that alterations in sinusoidal and biliary efflux of GSH can occur independent of changes in permeability of hepatocellular tight junctions. These findings suggest a role for protein kinase C in modulating the hepatic efflux of GSH.
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PMID:Effects of vasopressor hormones and modulators of protein kinase C on glutathione efflux from perfused rat liver. 192 46

Phorbol ester-induced translocation of the calcium/phospholipid-dependent protein kinase, protein kinase C (PKC), from soluble to particulate cell fractions was inhibited in primary cultures of hepatocytes isolated from rats chronically exposed to the liver tumor promoter phenobarbital (PB). Inhibition of translocation (34%) was significant after a 15-min treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA, 500 nM); an 85% inhibition was observed after 60 min. In contrast, the translocation responses to two non-phorbol ester activators of PKC, ATP (1 mM) and arginine-vasopressin (0.1 microM), were not significantly impaired. Assessment of total PKC specific activity revealed that translocation induced by TPA and the two nonphorbol activators was not associated with PKC degradation in hepatocytes from either control or PB-exposed rats. The defect in TPA-induced translocation was correlated with an impaired down-regulation of the hepatocyte surface receptor for epidermal growth factor in hepatocytes from PB-exposed rats. Chronic exposure to PB did not affect the total content or specific activity of PKC in whole liver, nor did it affect the distribution of PKC activity between soluble and particulate fractions in unstimulated liver or hepatocytes. However, both the diminished epidermal growth factor receptor response and the inhibition of TPA-induced PKC translocation were reversed by withdrawal of PB for 2 to 4 weeks. Hepatocytes isolated from female rats were found to contain a 3- to 4-fold greater PKC specific activity and content than hepatocytes from male rats. However, no sex-related differences were observed in PKC distribution or in the modulation of translocation by chronic PB exposure and withdrawal. Immunoblotting of partially purified liver extracts revealed that the defect in phorbol ester-induced translocation was not caused by altered expression of PKC isozymes. PKC isozymes II and III, but not I, were detected, and their amounts were unaffected by PB exposure, although higher levels were detected in female relative to male livers. These data demonstrate reversible inhibition of phorbol ester-induced PKC activation by the liver tumor promoter, PB, and suggest that PB alters a component of the PKC-signaling pathway other than the expression of PKC isozymes.
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PMID:Reversible and phorbol ester-specific defect of protein kinase C translocation in hepatocytes isolated from phenobarbital-treated rats. 198 78

In this study we investigated the role of protein kinases in activation of the Na(+)-H+ exchanger in inner medullary collecting duct (IMCD) cells. Monolayers, 24-48 h after achieving confluence, were made quiescent by 24 h incubation in 0.1% serum before study. Changes in pHi were measured with 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein. Phorbol myristate acetate (PMA), a synthetic analogue of diacylglycerol (DAG), was used to stimulate protein kinase C (PKC). In nominally HCO3(-)-free media containing 110 mM Na+ and 1 mM Ca2+, PMA addition increased pHi from 7.29 +/- 0.08 to 7.54 +/- 0.07 after 20 min. The increment in pHi was completely inhibited by 1 mM amiloride or by replacement of extracellular Na+ with choline but not inhibited by 1 mM N-ethylmaleimide, an inhibitor of active proton transport. Downregulation of PKC by overnight incubation of monolayers with PMA also prevented the rise in pHi upon subsequent challenge with PMA. Another active analogue of DAG, 1,2-dioleoyl-rac-glycerol, caused an increment in pHi similar to that produced by PMA, whereas 4 alpha-phorbol, an inactive analogue, did not stimulate Na(+)-H+ exchange. Bradykinin (10(-6) M), a phospholipase C-activating hormone, also induces alkalinization of IMCD cells similar to that produced by phorbol esters. Neither vasopressin (10(-7) M), which induces cellular accumulation of adenosine 3',5'-cyclic monophosphate (cAMP) and activation of protein kinase A (PKA), nor 8-bromo-cAMP (1 mM) changed pHi. Therefore in the IMCD cell activation of PKC but not PKA stimulates a rise in pHi via the Na(+)-H+ exchanger.
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PMID:Na(+)-H+ exchange is stimulated by protein kinase C activation in inner medullary collecting duct cells. 217 60

Regulation of urea transport by vasopressin in inner medullary collecting duct (IMCD) cells is thought to be important for the urinary concentrating mechanism. Isolated tubule perfusion studies suggest the existence of a saturable urea carrier. We have measured 14C-urea efflux in IMCD cells which were freshly isolated and grown in primary culture. Cells were isolated from rat papilla by collagenase digestion and hypotonic shock. In suspended cells, 14C-urea efflux (Jurea) from loaded cells was exponential with time constant 59 +/- 3 sec (SEM, n = 6, 23 degrees C). Jurea had an activation energy of 4.1 kcal/mole and was inhibited 42 +/- 7% by 0.25 mM phloretin and 30-40% by the high affinity urea analogues dimethylurea and phenylurea. Jurea was increased 40-60% by addition of vasopressin (10(-8) M) or 8-bromo-cAMP (1 mM); stimulated Jurea was inhibited 55 +/- 8% by the kinase A inhibitor H-8. Phorbol esters and epidermal growth factor did not alter Jurea. IMCD cells grown in primary culture were homogeneous in appearance with greater than fivefold stimulation of cAMP by vasopressin. The exponential time constant for urea efflux was 610 +/- 20 sec (n = 3). Jurea was not altered by vasopressin, cAMP or phloretin. Another function of in vivo IMCD cells, vasopressin-dependent formation of endosomes containing water channels, was absent in the cultured cells. These results demonstrate presence of a urea transporter on suspended IMCD cells which is activated by cAMP and inhibited by phloretin and urea analogues. The urea transporter and its regulation by cAMP, and cAMP-dependent apical membrane endocytosis, are lost after growth in primary culture.
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PMID:Urea transport in freshly isolated and cultured cells from rat inner medullary collecting duct. 217 46


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