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

Adenylate cyclase and the [8-lysine]vasopressin receptor were solubilized from pig kidney medulla membranes using the nonionic detergent Triton X-100. Optimal conditions for solubilization were under continuous stirring in a medium containing 0.5% (/v) Triton X-100, 100 mM Tris-HCl, pH 8, and 10 mM MgCl2. Both adenylate cyclase activity and [3H][8-lysine]vasopressin binding activity were recovered in a -26,000 X g supernatant of detergent-treated membranes. The yield of solubilized adenylate cyclase was nearly 100%. The soluble enzyme was no longer sensitive to antidiuretic hormone but was slightly activated by sodium fluoride. The affinity of the soluble receptor for [8-lysine]vasopresin was les than that of the membrane-bound receptor (mean apparent Km values, respectively 10(-7) M and 2 X 10(-8) M), however binding cooperativity was preserved. Hill coefficients were 1.42 for the soluble receptor and 1.50 for the membrane receptor. The soluble receptor discriminated as efficiently as did the membrane receptor between [8-lysine-a1vasopressin and oxytocin. The yield of spolubilized receptor was only 30% despite the fact that all binding activity had disappeared from the residual pellet of detergent-treated membranes. When the membranous receptors were occupied before solubilization and the latter was performed under conditions in which dissociation of the hormone-receptor comples is slow, i.e. at low temperature, 65% to 100% of the hormone-receptor complex was recovered in the soluble fraction. The soluble hormone-receptor complex partially dissociated on rewarming whereas the free hormone concentration was kept unchanged in the medium. The residual binding capacity, which was 30% of the initial value, was identical with that determined when the receptor was solubilized in free form before incubation with labeled hormone. It was concluded that (a) solubilization of the receptor molecules was complete, (b) during solubilization two forms of the receptor appear, of which only one is accessible to the hormone, (c) occupancy of the receptor by the hormone prevented the formation of the nonaccessible form, and (d) some component or components of the soluble fraction might be responsible for the loss in apparent affinity.
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PMID:Solubilization of the [8-lysine]vasopressin receptor and adenylate cyclase from pig kidney plasma membranes. 17 Feb 74

Recent data on the effects of neurohypophysial peptides at the cellular level are discussed with respect to the two basic processes involved in peptide hormone action--i.e., specific recognition of the information contained in the hormonal molecule and the transformation of this information into a stimulus leading to the final biological response. Four main aspects of this general problem are considered. A. Hormone-Receptor Interaction: Recent contributions in this field concern partial analysis of the three-dimensional conformation of oxytocin and vasopressin moleculal cells of the mammalian kidney. Conformational analysis of oxytocin and vasopressin molecules leads to the conclusion that, in solution, these peptides probably have a compact and highly stabilized three-dimensional configuration. Models have been proposed that provide a valuable clue to the interpretation of structure-activity relationships among natural hormones and many structural analogues. Binding studies with tritiated oxytocin and vasopressin have permitted determination of the kinetic parameters of hormone-receptor interaction in amphibian epithelial cells and mammalian kidney. B. Stimulus Generation: The nature of the primary stimulus generated by hormone-receptor interaction is still unknown. In the epithelial target cells of the amphibian skin and bladder and of the mammalian kidney, one of the first consequences of hormone-receptor interaction is the activation of membrane-bound adenylate cyclase. Analysis of the correlations between hormonal binding and adenylate cyclase activation suggests that activation is a function of receptor occupation rather than of the number of hormonal molecules interacting with the receptor per unit of time. On medullary adenylate cyclase of pig kidney, the relation between receptor occupancy and enzyme activation was found to be complex and nonlinear. The effects of several agents (calcium, nucleotides) on receptor occupancy and adenylate cyclase activation have been described. In mammalian uterus and other smooth muscle target cells, there is no evidence for direct involvement of cyclic AMP in the contractile response to oxytocin and other neurohypophysial peptides.
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PMID:Stimulus-response coupling in neurohypophysial peptide target cells. 17 91

The activities of enzymes related to the cellular action of vasopressin as well as the activities of other enzymes were studied in an animal model of hypothalamic diabetes insipidus. Rats with hereditary hypothalamic diabetes insipidus (homozygotes of Bratteboro strain) were found to have significantly lower renal medullary adenylate cyclase activity, either basal activity or activity stimulated by vasopressin, as compared with controls (heterozygotes of the same strain). There were no differences between the two strains in the activities of cyclic AMP phosphodiesterase, other hormone-sensitive adenylate cyclases, or the other renal medullary enzymes studied, which are apparently unrelated to the vasopressin action. The treatment of rats with hereditary hypothalamic diabetes insipidus with exogenous vasopressin increased the activity of renal medullary adenylate cyclase stimulated in vitro by maximal doses of vasopressin, but had no effect on the basal activity of adenylate cyclase or on the activity of cyclic AMP phosphodiesterase. This suggests that low adenylate cyclase activity in the renal medulla of rats with diabetes insipidus may be related to the subnormal concentrating ability observed in these animals.
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PMID:Renal medullary adenylate cyclase in rats with hypothalamic diabetes insipidus. 17 17

Free flow electrophoresis was employed to separate renal cortical plasma membranes into luminal (brush border microvilli) and contraluminal (basal-lateral membrane) fractions. During the separation adenylate cyclase activity was found to parallel the activity of Na+-K+-activated ATPase, an enzyme which is present in contraluminal but not in luminal membranes. In the basal-lateral membrane fraction the specific activities of adenylate cyclase and Na+-K+-activated ATPase were 4.4 and 4.6 times greater, respectively, than in the brush border fraction. The adenylate cyclase of the basal-lateral membrane fraction was specifically stimulated by parathyroid hormone which maximally increased enzyme activity eightfold. The biologically active (1-34) peptide fragment of paratyhroid hormone produced a 350% increase in adenylate cyclase activity. In contrast, calcitonin, epinephrine and vasopressin maximally stimulated the enzyme by only 55, 35 and 30%, respectively. These results indicate that adenylate cyclase, specifically stimulated by parathyroid hormone, is distributed preferentially in the contraluminal region of the plasma membrane of renal cortical epithelial cells.
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PMID:Distribution of parathyroid hormone-stimulated adenylate cyclase in plasma membranes of cells of the kidney cortex. 17 37

The epithelial cells of the toad urinary bladder are morphologically heterogenous. In order to relate the effect of vasopressin on cyclic AMP metabolism to cell type, the epithelial cells were separated by the density gradient technique of Scott, Sapirstein and Yoder (Science 184:797, 1974). The separation was verified by electron-microscopy and by observing that the band of cells enriched in mitochondria-rich cells was enriched in carbonic anhydrase activity compared to the band of granular cells. A large portion of cells collected from the gradient was considered to be nonviable, precluding further study of their function as intact cells. Vasopressin-stimulated adenylate cyclase activity in homogenates of granular cells was simular to that in homogenates of mitochondria-rich cells. Cyclic nucleotide phosphodiesterase activity was also similar in the two types of cell. Thus, the enzymes known to be involved in cyclic AMP metabolism in response to vasopressin appear to be located in both major cell types.
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PMID:Study of enzymes regulating vasopressin-stimulated cyclic AMP metabolism in separated mitochondria-rich and granular epithelial cells of toad urinary bladder. 17 64

The development of adenylate cyclase responsiveness to vasopressin and parathyroid hormone was studied using membrane fractions prepared from medullo-papillary and cortical portions of kidneys of 2-46-day-old rats. The development of vasopressin binding capacity was followed on the same preparations, using [3H]vasopressin. The characteristics of medullo-papillary adenylate cyclase response to vasopressin were identical in young and adult control animals as regards apparent Km values for [Lys8]vasopressin (3 X 10(-8) M), specificity towards the natural neurohypophysial peptides and the effects of Mg2+. However, the magnitude of maximal enzyme activation by vasopressin was much lower in very young than adult animals. Accordingly vasopressin responsiveness increased sharply between the 10th and 25th days but the magnitude of the maximal response only reached the adult value between the 30th and 45th days after birth. During both periods basal adenylate cyclase activity was almost independent of age. Specific vasopressin binding sites were detected on kidney medullo-papillary membranes from young animals. Vasopressin binding capacity and adenylate cyclase responsiveness to the hormone followed similar development patterns. However, the appearance of specific binding sites slightly preceded the onset of adenylate cyclase responsiveness. Basal cortical adenylate cyclase activity/mg protein was 12 times higher in 2-day-old rats than in the adult controls. It dropped with age but only fell to the adult value between the 25th and the 35th days after birth. For the youngest animals tested (2 days old), the increase in activity due to parathyroid hormone was about half the increase measured in adults, and gradually rose to about 75% of the adult response between the 2nd and 46th days after birth. Apparent Km values for parathyroid hormone were identical in young and adult animals (3.2 and 3.0 U/ml, respectively).
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PMID:Ontogenic development of antidiuretic hormone receptors in rat kidney: comparison of hormonal binding and adenylate cyclase activation. 17 22

Vasopressin-sensitive pig kidney adenylate cyclase is sensitive to several effectors, such as Mg2+, other divalent cations, and guanyl nucleotides. The purpose of the present study was to compare the main characteristics of adenylate cyclase activation by vasopressin, Mg2+, and GMPPNP, respectively. Mg2+ ions were shown to exert at least three different effects on adenylate cyclase. The substrate of the adenylate cyclase reaction is the Mg-ATP complex. Mg2+ interacts with an enzyme regulatory site. Finally, Mg2+ can modulate the hormonal response, with Mg2+ ions affecting the coupling function--that is, the quantitative relationship between receptor occupancy and adenylate cyclase activation. At all the magnesium concentrations tested, from 0.25 mM to 16 mM, adenylate cyclase activation was not a direct function of receptor occupancy. At low Mg2+ concentrations, adenylate cyclase activation dose-response curve to the hormone tended to be superimposable to the hormone dose-binding curve. These results suggest a role of magnesium at the coupling step between the hormone-receptor complex and adenylate cyclase response. Cobalt, but not calcium, ions could exert the same effects as Mg2+ ions on this coupling step. GMPPNP induced considerable adenylate cyclase activation (15 to 35 times the basal value). Activation by GMPPNP was highly time and temperature dependent. At 30 degrees C, a 20 to 60 min preincubation period in the presence of GMPPNP was needed to obtain maximal activation. The higher the dose of GMPPNP in the medium, the longer it took to reach equilibrium. At 15 degrees C, activation was still increasing with time after 3 hr preincubation in the presence of the nucleotide. GMPPNP was active in a 10(-8)M to 10(-5)M concentration range. Unlike the results obtained with lysine vasopressin, the kinetic characteristics of dose-dependent adenylate cyclase activation curves by GMPPNP were unaffected by varying Mg2+ concentrations except for the increase in velocity when raising Mg2+ concentration. It was not clear whether or not the activation processes by the hormone and by GMPPNP had common mechanisms.
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PMID:Vasopressin-sensitive kidney adenylate cyclase: modulation of the hormonal response. 17 20

Vasopressin increases the permeability of the total urinary bladder, an analogue of the mammalian renal collecting duct, to water and small solutes, especially the amide urea. We have observed that three general anesthetic agents of clinical importance, the gases methoxyflurane and halothane and the ultrashortacting barbiturate methohexital, reversibly inhibit vasopressin-stimulated water flow, but do not depress permeability to urea, or the the lipophilic solute diphenylhydantoin. In contrast to their effects in vasopressin-treated bladders, the anesthetics do not inhibit cyclic AMP-stimulated water flow, consistent with an effect on vasopressin-responsive adenylate cyclase. The selectivity of the anesthetic-induced depression of water flow suggests that separate adenylate cyclases and cyclic AMP pools may exist for control of water and urea permeabilities in to toad bladder. Furthermore, theophylline's usual stimulatory effect on water flow, but not its effect on urea permeability, was entirely abolished in methoxyflurane-treated bladders, suggesting that separate phosphodiesterases that control water and urea permeabilities are present as well. We conclude that the majority of water and urea transport takes place via separate pathways across the rate-limiting luminal membrane of the bladder cell, and that separate vasopressin-responsive cellular pools of cyclic AMP appear to control permeability to water and to urea.
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PMID:Selective inhibition of osmotic water flow by general anesthetics to toad urinary bladder. 18 13

1. Physiological concentrations of antidiuretic hormone increase diffusional water permeability but not measurable cyclic AMP content in the isolated papilla of the rat's kidney. 2. Theophylline (6 mM) increases diffusional water permeability and cyclic AMP content in the isolated papilla of the rat's kidney. 3. The increase in water permeability is detected with 5 muunits.ml-1 of ADH and is maximal with 50 muunits.ml-1. The same maximum was achieved with 6 mM theophylline. 4. Cyclic AMP and dibutyryl cyclic AMP both increase water permeability, but to a lesser extent than theophylline or ADH. 5. In the presence of theophylline, ADH causes a dose related generation of tissue cyclic AMP up to a dose of 2,000,000 muunits.ml-1. 6. Adenyl cyclase is increasingly activated by ADH up to doses of 2,000,000 muunits.ml-1. 7. These results suggest that while ADH activates the adenyl cyclase system and changes water permeability there are sufficient disparities to cast doubt on an exclusive role for cyclic AMP as the second messenger.
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PMID:The interrelationships between antidiuretic hormone, adenyl cyclase, tissue cyclic AMP and diffusional water permeability. 18 92

The diffusional water permeabilities of collecting ducts in the presence and absence of antidiuretic hormone have been measured in isolated papillae from normal, hypokalaemic and hypercalcaemic rats. In a similar in vitro situation the effect of antidiuretic hormone on the papillary content of cyclic AMP has been measured. The diffusional water permeability of collecting ducts in the absence of antidiuretic hormone did not differ significantly in papillae taken from the different groups of rats. The diffusional water permeability in the presence of ADH was 7.4 +/- 0.2 (S.E.M.) mum s-1 in collecting ducts taken from normal rats. In collecting ducts taken from hypokalaemic or hypercalcaemic rats the corresponding values were 5.9 +/- 0.3 and 5.8 +/- 0.5 mum s-1 respectively. This significant decrease (P less than 0.01) in the response to antidiuretic hormone would shift the point at which distal tubule fluid first attains isotonicity with the interstitium. If this shifts from cortex to medulla a greater amount of water enters the interstitium of the medulla and produces an impairment of maximal urinary concentrating ability and this defect could explain most of the observed results in hypokalaemic and hypercalcaemic. Cyclic AMP content of the tissue after the addition of ADH was reduced in papillae taken from hypokalaemic rats. This reduced activation of adenyl cyclase could be the mechanism responsible for the impaired response in water permeability but it is also possible that there is interference, with the chain of reactions mediating permeability changes, at a separate site.
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PMID:A study in vitro of the concentrating defect associated with hypokalaemia and hypercalcaemia. 18 84


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