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)

Colchicine, podophyllotoxin and vinblastine have been found to inhibit the action of vasopressin on water movement in the toad urinary bladder. Tubulin is the major colchicine binding component of toad bladder epithelial cells, accounting for approximately 3.3% of the total cell protein. More than 99% of the tubulin is found in the soluble fraction after sonication, the remainder is in the particulate fraction. Similar to the characteristics of the binding of colchicine to tubulins from other sources, the binding of colchicine to toad bladder tubulin is temperature- and time-dependent, is inhibited competitively by podophyllotoxin (Ki= 5.5 x 10(-7)m), and has a binding constant of 1 X 10(6) liters/mole at 37 degrees. Binding activity decays according to first-order kinetics and is stabilized by vinblastine. The characteristics of the interactions of colchicine and podophyllotoxin with epithelial cell tubulin in vitro closely parallel the ability of these drugs to inhibit the response to vasopressin in vivo. These results, coupled with those of functional and morphological studies, support the view that the ability of these drugs to affect vasopressin-induced water movement across toad bladder epithelial cells is related to the depolymerization of cytoplasmic microtubules.
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PMID:Evidence for involvement of microtubules in the action of vasopressin in toad urinary bladder. II. Colchicine binding properties of toad bladder epithelial cell tubulin. 9 70

Active sodium transport and CO2 production were measured simultaneously in toad bladders mounted in membrane chambers. The rate of sodium transport was varied by changing the concentration of sodium in the mucosal bath (substitution with choline), by adding vasopressin, by adding metabolic substrates and by adding malonate, and the ratio of the change of sodium transport and CO2 production was determined Mean values for deltaNa/deltaCO2 (equiv/mole) were: Na in equilibrium choline 18.3 +/- 1.1; vasopressin 15.5 +/- 2.8; and pyruvate (corrected for the increment in "nontransport" CO2) 15.4 +/- 3.5. Based on previously determined values for the respiratory quotient (R.Q.), calculated mean values for deltaNa/deltaO2 ranged between 15.5 and 18.5 equiv/mole. It appears that basal metabolism does not contribute to metabolism supporting sodium transport when the rate of sodium transport is varied. "Transport" metabolism appears much more responsive to changes in the availability of endogenous and exogenous substrates than does "nontransport" metabolism. We conclude that "transport" and "nontransport" metabolism are functionally separated in the toad bladder.
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PMID:Interrelationships of sodium transport and carbon dioxide production by the toad bladder: response to changes in mucosal sodium concentration, to vasopressin and to availability of metabolic substrate. 40 60

A radioimmunological method for the determination of the human antidiuretic hormone [8-arginine]-vasopressin (AVP), is described in detail. The antiserum has been raised in rabbits injected with AVP adsorbed onto charcoal particles and is used at a final dilution of 1:200,000. It contains antibodies directed specifically against the C-terminal tripeptide and possesses a high association constant of 8.2 x 10(12) 1/mole. AVP is labelled in monoiodinated form (as proven after pronase digestion) at a high specific activity close to the theoretical maximum after purification from unlabelled hormone on Sephadex gel. The standard curves are characterized by a Bo of 55%, a limit of detection ascertained at least at 3 pg (10% displacement) and a 50% displacement achieved with 35.5 pg. The index of precision lambda ranges from 0.033 to 0.042. The conditions of the assay (buffer's composition and pH, timing) were systematically varied and tested. In addition the result of immunization of chicken with AVP is reported. The assay is adequate for the measurement of AVP in urine and plasma and will be described in forthcoming papers.
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PMID:Radioimmunoassay of (8-arginine)-vasopressin. I. Methodology. 124 61

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

To determine the role of arginine vasopressin (AVP) in stress-induced release of anterior pituitary hormones, AVP antiserum or normal rabbit serum (NRS) was micro-injected into the 3rd ventricle of freely-moving, ovariectomized (OVX) female rats. A single 3 microliter injection was given, and 24 hours later, the injection was repeated 30 min prior to application of ether stress for 1 min. Although AVP antiserum had no effect on basal plasma ACTH concentrations, the elevation of plasma ACTH induced by ether stress was lowered significantly. Plasma LH tended to increase following ether stress but not significantly so; however, plasma LH following stress was significantly lower in the AVP antiserum-treated group than in the group pre-treated with NRS. Ether stress lowered plasma growth hormone (GH) levels and this lowering was slightly but significantly antagonized by AVP antiserum. Ether stress also elevated plasma prolactin (Prl) levels but these changes were not significantly modified by the antiserum. To evaluate any direct action of AVP on pituitary hormone secretion, the peptide was incubated with dispersed anterior pituitary cells for 2 hours. A dose-related release of ACTH occurred in doses ranging from 10 ng (10 p mole)-10 micrograms/tube, but there was no effect of AVP on release of LH. The release of other anterior pituitary hormones was also not affected except for a significant stimulation of TSH release at a high dose of AVP. The results indicate that AVP is involved in induction of ACTH and LH release during stress. The inhibitory action of the AVP antiserum on ACTH release may be mediated intrahypothalamically by blocking the stimulatory action of AVP on corticotropin-releasing factor (CRF) neurons and/or also in part by direct blockade of the stimulatory action of vasopressin on the pituitary. The effects of vasopressin on LH release are presumably brought about by blockade of a stimulatory action of AVP on the LHRH neuronal terminals.
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PMID:Role of arginine vasopressin in control of ACTH and LH release during stress. 298 9

Osmotic water permeability of the apical membrane of toad urinary epithelium is increased greatly by vasopressin (VP) and is associated with exocytic addition of granules and aggrephores at the apical surface. To determine the physiological role of granule exocytosis, we measured the osmotic water permeability and membrane fluidity of isolated granules, surface membranes and microsomes prepared from toad bladder in the presence and absence of VP. Pf was measured by stopped-flow light scattering and membrane fluidity was examined by diphenylhexatriene (DPH) fluorescence anisotropy. In response to a 75 mM inward sucrose gradient, granule size decreased with a single exponential time constant of 2.3 +/- 0.1 sec (SEM, seven preparations, 23 degrees C), corresponding to a Pf of 5 x 10(-4) cm/sec; the activation energy (Ea) for Pf was 17.6 +/- 0.8 kcal/mole. Under the same conditions, the volume of surface membrane vesicles decreased biexponentially with time constants of 0.13 and 1.9 sec; the fast component comprised approximately 70% of the signal. Granule, surface membrane and microsome time constants were unaffected by VP. However, in surface membranes, there was a small decrease (6 +/- 2%) in the fraction of surface membranes with fast time constant. DPH anisotropies were 0.253 (granules), 0.224 (surface membranes) and 0.190 (microsomes), and were unaffected by VP. We conclude: (1) granules have among the lowest water permeabilities of biological membranes, (2) granule water permeability is not altered by bladder pretreatment with VP, (3) granule membrane fluidity is remarkably lower than that of surface and microsomal membranes, and (4) rapid water transport occurs in surface membrane vesicles. The unique physical properties of the granule suggests that apical exocytic addition of granule membrane may be responsible for the low water permeability of the unstimulated apical membrane.
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PMID:Very low osmotic water permeability and membrane fluidity in isolated toad bladder granules. 314 39

Flexibility of various structural domains of neurophysin and neurophysin-neurohypophyseal hormone complexes has been investigated through the fast rotational motion of fluorophores in highly viscous medium. Despite seven intrachain disulfide links, it is shown that some domains of neurophysin remain highly flexible. Dimerization of neurophysin does not affect the structural integrity of the individual subunits, each subdomain being conformationally equivalent within each protomer of the unliganded dimer. The absence of heterogeneous fluorescence anisotropy precludes the existence of a dimer tautomerization equilibrium. Binding of the hormonal ligands to neurophysin dimer promotes a large conformational change over the whole protein structure as assessed by differential alterations of the flexibility-rigidity and intrasegmental interaction properties of domains that do not participate directly to the dimerization/binding areas. The order of free-energy coupling between ligand binding and protein subunit association has been evaluated. Data are consistent with a model in which the first mole of bound ligand stabilizes the dimer by increasing the intersubunit contacts while the second mole of ligand induces most of the described conformational change. Accordingly, the positive cooperativity between the two dimeric binding sites is linked mainly to the binding of the second ligand. The induced structural change is perceived differently by each subunit as assessed by opposite local motions of Tyr49 in each liganded protomer and leads to the formation of a dimeric complex with a global pseudospherical symmetry although containing domains of local asymmetry.
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PMID:Conformational flexibility of neurophysin as investigated by local motions of fluorophores. Relationships with neurohypophyseal hormone binding. 401 92

1. When applied directly to the brain, angiotensin II amide, as either the valine(5) octapeptide, causes rats in normal fluid balance to drink water.2. The drinking response to angiotensin injections is copious, rapid, repeatable within the same test session, and stable over months of testing in the same animal.3. The response is motivationally potent and specific. After injection the animals move directly to the source of water and drink. There is typically no preliminary hyperactivity or subsequent depression. The animals do not eat, gnaw or exhibit other behaviours that are not normally seen during spontaneous drinking. The injections rouse sleeping animals to drink and interrupt eating in animals deprived of food for two days.4. The region of the brain that is most sensitive to angiotensin includes the anterior hypothalamus, the preoptic region, and the septum including the nucleus accumbens.5. Intracranial renin elicited drinking. Bradykinin and vasopressin did not, nor did adrenaline, noradrenaline or aldosterone. In the most sensitive region, sites positive for angiotensin also yielded drinking to carbachol.6. Responses were obtained with 5 ng (ca. 5 p-mole) and occurred reliably with 50 ng angiotensin or more. The dose-response curve for amount drunk rose from 5 to 100 ng and levelled off thereafter. Angiotensin is therefore the most potent dipsogen known and is effective at doses that are reasonably within the concentration range for circulating endogenous angiotensin.7. Injections into the sensitive region of doses of angiotensin that were effective for drinking did not produce peripheral haemodynamic changes in lightly anaesthetized rats.8. This work strengthens the suggestion that angiotensin is a natural hormone of drinking behaviour that participates in extracellular thirst by its release from the kidney and subsequent direct action on a specific chemoreceptive region in the anterior diencephalon and limbic lobe.
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PMID:Drinking induced by injection of angiotensin into the rain of the rat. 432 23

Toad bladders were challenged with vasopressin at one temperature, fixed on the mucosa with 1% glutaraldehyde, and then subjected to an osmotic gradient at another temperature. Thus, the temperature dependence of vasopressin action on membrane permeability was distinguished from the temperature dependence of osmotic water flux. As the temperature was raised from 20 degrees to 38 degrees C, there was a substantial increase in the velocity of vasopressin action, but osmotic flux was hardly affected. In this range of temperature the apparent energy of activation for net water movement across the bladder amounted to only 1.2 kcal/mole, a value well below the activation energy for bulk water viscosity. It is suggested that osmotic water flux takes place through narrow, nonpolar channels in the membrane. When the temperature was raised from 4 degrees to 20 degrees C, both vasopressin action as well as osmotic water flux were markedly enhanced. Activation energies for net water movement were now 8.5 kcal/mole (4 degrees -9 degrees C) and 4.1 kcal/mole (9 degrees -20 degrees C), indicating that the components of the aqueous channel undergo conformational changes as the temperature is lowered from 20 degrees C. At 43 degrees C bladder reactivity to vasopressin was lost, and irreversible changes in selective permeability were observed. The apparent energy of activation for net water movement across the denatured membrane was 6.6 kcal/mole. Approximately 1 microosmol of NaCl was exchanged for 1 microl of H(2)O across the denatured membrane.
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PMID:Temperature dependence of vasopressin action on the toad bladder. 462 51

The activation energy (E(A)) for the diffusion of water across the epithelial cell layer of the toad bladder was determined in the absence and presence of vasopressin. An experimental approach was employed which minimized the effects of unstirred layers and the thick supporting layer of the bladder on the measurement of water diffusion. E(A) in the absence of vasopressin was 11.7 +/-1.4 kcal.mole(-1); after vasopressin it was 10.6+/-1.1 kcal.mole(-1). The difference between the two values was not significant. The results are consistent with an increase in the number rather than the size of aqueous channels in the cell membrane, a finding which differs from the generally held view that the hormone increases the radius of pores in the membrane.
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PMID:Activation energy for water diffusion across the toad bladder: evidence against the pore enlargement hypothesis. 555 4


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