UNIPROT:P01185 - FACTA Search

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Query: UNIPROT:P01185 (vasopressin)
23,126 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Urea and water transport across the toad bladder can be separately activated by low concentrations of vasopressin or 8 Br-cAMP. Employing this method of selective activation, we have determined the reflection coefficient (sigma) of urea and other small molecules under circumstances in which the bladder was transporting urea or water. An osmotic method for the determination of sigma was used, in which the ability of a given solute to retard water efflux from the bladder was compared to that of raffinose (sigma = 1.0) or water (sigma = 0). When urea transport was activated (low concentration of vasopressin), sigma for urea and other solutes was low, (sigma urea, 0.08--0.39; sigma acetamide, 0.55; sigma ethylene glycol, 0.60). When water transport was activated (0.1 mM 8 Br-cAMP) sigma urea approached 1.0 sigma urea also approached 1.0 at high vasopressin concentrations. In a separate series of studies, sigma urea was determined in the presence of 2 x 10(-5) M KMnO4 in the luminal bathing medium. Under these conditions, when urea transport is selectively blocked, sigma urea rose from a value of 0.12 to 0.89. Thus, permanganate appears to "close" the urea transport channel. These findings indicate that the luminal membrane channels for water and solutes differ significantly in their dimensions. The solute channels, limited in number, have relatively large radii. They carry a small fraction (approximately 10%) of total water flow. The water transport channels, on the other hand, have small radii, approximately the size of a water molecule, and exclude solutes as small as urea.
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PMID:Membrane pathways for water and solutes in the toad bladder: II. Reflection coefficients of the water and solute channels. 22 14

Previous in vivo studies showed that microtubules are involved in the cellular action of vasopressin. In order to analyze the role of renal medullary microtubules, a system was developed which would allow the study of the assembly of tubulin in renal medulla extracts into microtubules in vitro. The assembly of tubulin into microtubules occurred in renal medullary cytosol (100 000 times g supernatant) under specific conditions which include pre-concentration of cytosol by ultrafiltration, the presence of ethylene glycol bis(2-aminoethyl)ether tetraacetic acid (EGTA) and 4 M glycerol, and warming at 37 degrees C. Formation of microtubules, which sedimented at 100 000 times g, was proved by (a) an increase in the apparent [3H]colchicine-binding activity of depolymerized pellets, (b) appearance of typical microtubules as shown by electron microscopy, and (c) by the increase in the quantity of microtubular protein analyzed by polyacrylamide gel electrophoresis. Vinblastine at a concentrationof 10(-6) M completely blocked formation of microtubules. A slight increase of ionized calcium in the polymerization mixture also prevented microtubule assembly; this inhibitory effect of ionized calcium was present at concentrations as low as 10(-4) M. Blockade of microtubule assembly by the increase in concentration of ionized calcium or by vinblastine may be the basis of known inhibitory effect of these two agents upon the hydroosmotic effect of vasopressin in vivo.
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PMID:Studies on in vitro polymerization of tubulin from renal medullary extracts. 118 Sep 65

We studied cyclic 3',5'-nucleotide phosphodiesterase (PDE) isozymes and their role in adenosine 3',5'-cyclic monophosphate (cAMP) and cGMP metabolism in a rat inner medullary collecting duct (IMCD) cell line. The homogenized and fractionated IMCD cells of cAMP-PDE and all of cGMP-PDE activity were found in the cytosol. The majority of cytosolic cAMP-PDE (greater than 50%) was isozyme PDE-IV; the Ca(2+)-calmodulin-sensitive PDE-I was present only in cytosol. Preincubation of IMCD cells with PDE-IV inhibitor rolipram markedly (5x) enhanced levels of cAMP both basal and in the presence of [Arg8]vasopressin (AVP). Cilostamide (for PDE-III) or vinpocetine had no effect, whereas PDE-I inhibitor 8-methoxymethyl-3-isobutyl-1-methylxanthine (8-MeoM-IBMX) enhanced AVP-dependent cAMP levels. Exposure of IMCD cells to 2 microM ionomycin decreased both basal and AVP-stimulated cAMP. Depletion of Ca2+ by preincubation of IMCD cells in the Ca(2+)-free medium with ethylene glycol-bis (beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid markedly enhanced the stimulatory response of cAMP to AVP, and addition of 8-MeoM-IBMX further enhanced the AVP response. The levels of cGMP, basal or in response to atriopeptin (ANP), were not affected by PDE-V inhibitor zaprinast, but both inhibitors of PDE-I, 8-MeoM-IBMX and vinpocetine, increased basal cGMP, and 8-MeoM-IBMX also increased cGMP levels enhanced by ANP. The depletion of Ca2+ from IMCD cells alone had no effect on cGMP levels, but effects of 8-MeoM-IBMX and vinpocetine on the ANP-stimulated cGMP levels were enhanced.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Cyclic 3',5'-nucleotide diesterases in dynamics of cAMP and cGMP in rat collecting duct cells. 132 Mar 33

Isolated skate (Raja erinacea) hepatocytes swollen in hypotonic media exhibited a regulatory volume decrease (RVD) that was associated with only a small increase in K+ or 86Rb+ efflux but a substantial increase in the release of taurine, an amino acid found in high concentrations in skate hepatocytes. Taurine efflux was stimulated in media made hypotonic by addition of H2O or removal of NaCl, as well as in cells swollen in isotonic media containing rapidly penetrating solutes (202 mM ethylene glycol or 202 mM additional urea substituted for 101 mM NaCl), suggesting that cell swelling rather than hyposmolarity is the stimulus for the activation of taurine release. In contrast, release of glutathione, L-[14C]alanine and other alpha-amino acids (e.g., threonine, serine, glutamate, glutamine, glycine, or valine) was unaffected by dilution with 40% H2O. Taurine efflux was not altered by replacement of extracellular Na+ with choline+ or K+ and was only slightly diminished by replacing Cl- with NO3-. Addition of 50 mM taurine or hypotaurine to the incubation media also had no effect on volume-stimulated [14C]taurine efflux, suggesting that the taurine concentration gradient across the plasma membrane is not the driving force. Volume-stimulated taurine transport was temperature sensitive, 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid inhibitable (0.5 mM), and nearly completely blocked by metabolic inhibitors (2,4-dinitrophenol, KCN, sodium azide, oligomycin, carbonyl cyanide m-chlorophenylhydrazone, and antimycin A), suggesting an active energy-dependent process. Sulfhydryl-reactive reagents (N-ethylmaleimide, diamide, iodoacetate, tert-butyl hydroperoxide, and mercury) also blocked volume-stimulated taurine efflux, whereas efflux was unaffected by Ca2+ ionophore, phorbol ester, dibutyryl-adenosine 3',5'-cyclic monophosphate, vasopressin, or pretreatment with ouabain or furosemide. N-ethylmaleimide, diamide, 2,4-dinitrophenol, and iodoacetate plus KCN also inhibited the RVD. These findings suggest that, in contrast to hepatocytes from most vertebrate species, RVD in skate hepatocytes is associated with the release of only a small fraction of intracellular K+ but a substantial fraction of intracellular taurine and perhaps other organic osmolytes. This volume-activated taurine transport mechanism is energy and sulfhydryl group dependent and is not related to the taurine concentration gradient across the skate hepatocyte plasma membrane.
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PMID:Taurine transport in skate hepatocytes. II. Volume activation, energy, and sulfhydryl dependence. 155 Feb 35

Chemical and photoaffinity cross-linking experiments as well as ligand affinity blotting techniques were used to label the V1 vasopressin receptor. In order to determine the optimal reaction conditions, pig liver membranes were incubated with 5 nM [8-lysine]vasopressin (LVP) labeled with 125I and then cross-linked with the use of DMS (dimethyl suberimidate), EGS [ethylene glycol bis(succinimidyl succinate)] or HSAB (hydroxysuccinimidyl p-azidobenzoate) at different final concentrations. Consistently, EGS was found to label with high yield one band of Mr 60,000 in rat and pig liver membranes when used at a final concentration between 0.05 and 0.25 mM. The protein of Mr 60,000 is labeled in a concentration-dependent manner when pig liver membranes are incubated with increasing concentrations of 125I-LVP and then cross-linked with EGS. The label was displaced by increasing concentrations of unlabeled LVP or d(CH2)5 [Tyr2(Me),-Tyr9(NH2)]AVP (V1/V2 antagonist). A protein band of similar molecular mass was cross-linked with 125I-LVP in rat liver membranes. The reaction was specific since the incorporation of label into the protein of Mr 60,000 was inhibited by LVP, [8-arginine]vasopressin (AVP), the V1/V2-antagonist, and the specific V1-antagonist d(CH2)5 [Tyr2(Me)]AVP, only partially by [des-Gly9]AVP (V2-agonist) and by oxytocin, and not at all by angiotensin II. Incubation of nitrocellulose containing membrane proteins from pig liver with 125I-LVP showed the labeling of a band of Mr 58,000 that is inhibited by an excess of unlabeled LVP. This band of Mr 58,000 seems to correspond with the protein of Mr 60,000 revealed by the cross-linking experiment.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Identification of the V1 vasopressin receptor by chemical cross-linking and ligand affinity blotting. 183 97

The mechanism for the vasopressin- and epinephrine-induced decrease in bile formation and increase in sinusoidal efflux of glutathione was investigated in rat livers perfused with recirculating fluorocarbon emulsion. Vasopressin and epinephrine transiently decreased bile flow and excretion of endogenous bile acids and glutathione and increased the bile/perfusate ratio of [14C]sucrose, suggesting an increase in junctional permeability, but had no effect on the bile/perfusate ratio of [3H]polyethylene glycol-900. The decreased biliary glutathione was balanced by an increase in sinusoidal efflux, such that total hepatic release remained unchanged. The adrenergic antagonist dihydroergotamine blocked the effects of epinephrine. To examine whether an increase in junctional permeability per se could account for the changes in glutathione efflux, biliary permeability was increased by either bile duct ligation, lowering of perfusate Ca2+ concentration with ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA), or addition of taurolithocholate, a cholestatic bile acid. All three maneuvers produced a decrease in biliary glutathione excretion and a concomitant increase in sinusoidal glutathione efflux, whereas total glutathione release was largely unaffected. The effects of EGTA were partially reversed if CaCl2 was reintroduced into the perfusate. Because the GSH/GSSG ratio in perfusate could not be measured in this experimental system due to the spontaneous oxidation of GSH to GSSG, additional experiments in the nonrecirculating mode examined the effects of vasopressin and bile duct ligation on sinusoidal release of GSH and GSSG. In control livers there was no detectable GSSG in perfusate (less than 0.5 nmol.min-1.g-1). After vasopressin administration, the additional sinusoidal glutathione was mainly as GSH, although there was also a significant amount of GSSG (1-2 nmol.min-1.g-1). The additional glutathione released into perfusate after bile duct ligation was 47% as GSSG. When vasopressin was administered to livers whose bile duct had been ligated, its ability to enhance sinusoidal glutathione release was diminished, suggesting that the effects of vasopressin and bile duct ligation are not additive. These observations support previous findings that vasopressin and epinephrine can modulate hepatocyte tight junctional permeability and demonstrate that these hormones produce cholestasis and inverse changes in sinusoidal and biliary glutathione efflux. Other maneuvers that increased biliary permeability to [14C]sucrose also produced cholestasis and a redistribution of glutathione efflux from bile to perfusate, suggesting that an increase in junctional permeability may allow biliary glutathione to reflux from bile to plasma.
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PMID:Cholestasis, altered junctional permeability, and inverse changes in sinusoidal and biliary glutathione release by vasopressin and epinephrine. 211 13

Extracellular ATP stimulated adipocyte pyruvate dehydrogenase in a time- and dose-dependent manner with an EC50 of 0.1 mM. The maximal effect was observed at 0.5 mM ATP after a 15-min incubation with a lag period of about 5 min. Depletion of intracellular Ca2+ with ethylene glycol bis(beta-aminoethyl ether) N,N'-tetraacetic acid reduced the effect of ATP by 50% and completely abolished the stimulatory effect of vasopressin on adipocyte pyruvate dehydrogenase but had no effect on the stimulation induced by insulin or adenosine. The effects of insulin and ATP on pyruvate dehydrogenase were glucose-dependent whereas the effect of adenosine was glucose-independent. Furthermore, ATP, like insulin, partially blocked the stimulatory effect of isoproterenol on phosphorylase. Adenosine, at a concentration of 1 mM, did not affect either basal or isoproterenol-stimulated phosphorylase activities. It is concluded that ATP activates adipocyte pyruvate dehydrogenase by at least two separate mechanisms: one is Ca2(+)-dependent and the other is Ca2(+)-independent. However, neither is the result of the formation of adenosine from ATP through hydrolysis.
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PMID:Insulin-like effects of ATP on adipocyte pyruvate dehydrogenase and phosphorylase. 240 52

Maximal doses of vasopressin increase the permeability of the skins of Bufo bufo and Rana esculenta to urea, ethylene glycol, glycerol, erythritol, beta-alanine, leaving virtually unmodified that of mannitol and antipyrine. These results demonstrate that the response to vasopressin is quite different in amphibian skins as compared to the bladders. A careful analysis of the effects of vasopressin on non-electrolyte permeability as a function of their molecular weight demonstrates that hormone elicits the formation of pores with a diameter inferior to 4 A. Under vasopressin treatment the skins exhibit a selectivity for polyhydroxylated molecules as compared to urea and beta-alanine. This selectivity is not due to active of facilitated transport and is not impaired by phloretin or DTNB which selectively blocks the permeability of urea or ethylene glycol in erythrocytes. It is proposed that the site of such selectivity is located in other plasma membranes of the epithelium.
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PMID:Effect of vasopressin on the permeability of non electrolytes across the skins of Rana esculenta and Bufo bufo. 241 8

The regulation of cytosolic calcium in LLC-PK1 cells by various agonists was characterized. Arginine vasopressin (AVP, 100 nM) rapidly increased cytosolic calcium (Caf) measured with fura-2 from a basal level of 65 +/- 5 to 516 +/- 102 nM followed by a return to a plateau level of 128 +/- 18 nM. Similar responses to 100 nM lysine vasopressin were seen. AVP also increased adenosine 3',5'-cyclic monophosphate (cAMP) as previously documented for these cells. A V2-selective AVP analogue increased cAMP without affecting Caf, whereas two V1-receptor antagonists prevented the Caf response to AVP without altering the cAMP response. Increasing cellular cAMP with forskolin, cholera toxin, or stable cAMP analogues did not affect Caf or the response of Caf to AVP. Both adenosine and ATP produced large Caf transients at concentrations of 1-10 microM in both calcium-containing media and after acute chelation of medium Ca with ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA). The A1-selective adenosine analogue, (R-phenyl-isopropyl)-adenosine, and the A2-selective analogue, 5'-(N-ethyl)-carboxamido-adenosine, both produced Caf responses similar to adenosine. The Caf responses to adenosine and its analogues but not to ATP were blocked by the adenosine receptor antagonist, 8-cyclopentyl-1,3-dipropylxanthine. Islet-activating protein, pertussis toxin, inhibited the Caf response to adenosine and enhanced the cAMP response to AVP. Responses to all agonists were demonstrable in greater than 80% of single cells studied by microfluorometry, and individual cells responded to multiple agonists. These studies indicate that the Caf and cAMP responses to AVP in the LLC-PK1 cell line involve separate receptors, and they document the presence in this cell line of at least two types of receptors for exogenous purines.
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PMID:Alterations of cytosolic calcium in LLC-PK1 cells induced by vasopressin and exogenous purines. 254 21

An enriched preparation of neurosecretory granules from bovine pituitary neural lobes was used as a source of processing enzymes possibly involved in the cleavage of the proocytocin/neurophysin precursor. A synthetic eicosapeptide reproducing the entire (1-20) sequence of the NH2-terminal domain of the bovine ocytocin/neurophysin precursor was used as a substrate to monitor an endoprotease activity cleaving at the Lys11-Arg12 doublet. The 58-kDa endoprotease detected in the lysate of neurohypophyseal granules produced a single cleavage, after the doublet, at the Arg12-Ala13 peptide bond. This endoprotease with pHi 6.9 and 7.2 exhibits maximal activity at pH around neutrality (7.0) and was strongly inhibited by divalent cation chelating agents [ethylenediaminetetraacetic acid and ethylene glycol bis(beta-aminoethyl ether)-N,N,N',-N'-tetraacetic acid] and to some extent by p-(chloromercuri)benzoate and p-(chloromercuri)benzenesulfonic acid, while phenylmethanesulfonyl fluoride and pepstatin were not active. This endoprotease action was sensitive to any modification of the substrate at either basic amino acid of the doublet since replacement of either L-Lys11 or L-Arg12 by D-Lys or D-Arg and by L-Nle abolished the cleavage reaction. In contrast, reversal of the polarity of the doublet in [Arg11,Lys12]proocytocin/neurophysin(1-20) had no effect on the mode of endoproteolytic cleavage as well as modifications of Gly10 (replaced by Ala10). It is concluded that the selectivity of this endoprotease, which may be involved in the primary event occurring in proocytocin/neurophysin processing, is strictly dependent upon the integrity of the basic doublet but that other parameters determined by the amino acid sequence around this doublet may play an important role.
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PMID:Partial purification and functional properties of an endoprotease from bovine neurosecretory granules cleaving proocytocin/neurophysin peptides at the basic amino acid doublet. 282 69

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