Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Oxytocinase (cystyl-aminopeptidase) [EC 3.4.11.3] was isolated from monkey placenta in a purified form by a six-step prodedure comprising extraction from monkey placenta homogenate, ammonium sulfate fractionation, repeated chromatography on hydroxylapatite, chromatography on a column of DEAE-cellulose and gel filtration on a column of Sephadex G-200. The purified enzyme showed a single band on polyacrylamide disc electrophoresis. Oxytocin was inactivated by this enzyme preparation. The enzyme hydrolyzed several aminoacyl-beta-naphthylamides. A terminal amino group was required for enzyme activity. The molecular weight of the purified enzyme was estimated to be 87,000 by gel filtration and 83,000 by sodium dodecyl sulfate gel electrophoresis. Other properties of the enzyme, the effects of metal ions and various chemical reagents on the enzyme activity, the pH optimum, and Km values for a number of aminoacyl-beta-naphthylamides were also examined.
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PMID:Purification and properties of oxytocinase (cystine amino-peptidase) from monkey placenta. 1 46

Slices from ox neurohypophyses were incubated in a calcium-free medium with the ionophores A23187 or X537A. X537A (5 X 10(-5) mol/l) caused a marked release of vasopressin, neurophysin and protein to the medium. A23187 (2 X 10(-5) mol/l) did not cause any release by itself, but when Ca2+ was added to the medium in the presence of the ionophore, an increase in the release of vasopressin, neuorphysin and protein occurred. Release of lactate dehydrogenase and peptidase were not affected by the ionophores. The secretion caused by A23187 was abolished by D600 (a verapamil analogue) (2 X 10(-5) mol/l) whereas the effect of X537A was unchanged. The effects of X537A were strongly inhibited by removal of sodium from the medium. Re-addition of sodium to the medium caused a marked release. Gramicidin (10(-6) or 5 X 10(-5) mol/l) had no effect on secretion. Efflux of 45Ca2+ from pre-loaded slices was drastically reduced in a sodium-free medium. X537A caused an increase in the efflux rate of 45Ca2+ both in medium with a normal concentration of sodium and when slices had been incubated in a sodium-free medium. A23187 and X537A both released 45Ca2+ from a neurohypophyseal mitochondrial fraction. When sodium in a concentration of 20 mmol/l was added to this fraction, the Ca2+ accumulation was inhibited. This effect was reduced by inorganic phosphate up to a concentration of 2 mmol/l.
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PMID:Calcium and stimulus secretion coupling in the neurohypophysis. V. The effects of the Ca2+ ionophores A23187 and X537 A on vasopressin release and 45Ca2+ efflux; interactions with sodium and a verapamil analogue (D600). 6 Aug 66

Administration of pituitrin, vasopressin, and oxytocin to rats during spontaneous micturition increases diuresis and sodium excretion by reducing tubular reabsorption. In adrenalectomized rats these preparations have no diuretic effect and increased sodium excretion is observed only after administration of vasopressin. After hypophysectomy the diuretic effect of the preparations disappears but they still increase sodium excretion. It is postulated that the diuretic effect of the neurohypophyseal hormones is connected with activation of the pituitary-adrenal system, whereas some additional mechanism is involved in their effect on sodium excretion.
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PMID:Mechanism of action of neurohypophyseal hormones on sodium excretion and diuresis. 6 76

During hypertonic saline induction, the evolution of intrauterine pressure, the oxytocin response and abortion were delayed in naproxen-treated patients. The PG synthesis inhibitors naproxen, mefenamic acid and ibuprofen decreased the high uterine resting pressure ('tone'), the frequency of contractions but not always the active pressure ('amplitude') in dysmenorrheic patients, with a coincident decrease in pain. The naproxen-sodium treatment decreased prostaglandins F and E in menstrual blood and uterine jet washings by 60--80 per cent.
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PMID:Suppression of uterine activity by prostaglandin synthetase inhibitors. 11 65

In experiments on isolated gall-bladders (GB) of frogs, the transport rate of NaCl-isotonic solution by GB epithelial cells was inversely proportionate to the sodium content in them. Under oxytocin action (20 mE/ml) the absorption was inhibited and simultaneously the intracellular sodium content increased. Replacement of NaCl by sucrose solution caused a complete inhibition of absorption for 5--15 min. During this time, tissue cells excreted a considerable amount of their sodium, in result of which the intracellular amount of sodium decrease by 2.0-2.5 times. Oxytocin caused the inhibition of both the sodium transport from cells and the Na-K--ATPase activity. Obviously, the inhibitory action of oxytocin upon sodium transport from GB cells is due to a decrease of the transport activity of Na, K--ATPase under the action of hormone.
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PMID:[The concentration of electrolytes and water in the walls of the frog gall bladder following absorption of an isotonic fluid]. 13 Feb 68

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

Partly purified rat neurophysin was tested for its possible natriuretic activity in acutely hypophysectomized saline-loaded rats (hypophysectomized 2 h prior to saline infusion). Such animals were unable to excrete the saline load. When partly purified rat neurophysin was injected i. p. in a dose of 40 microgram per animal (which corresponds to its content in one rat posterior pituitary) before saline loading, the sodium excretion was not different from that found in acutely hypophysectomized animals, but it was significantly lower than in normal saline-loaded rats. It was concluded that any apparent natriuretic effect of rat neurophysin could not be established by the present experiments under the experimental conditions used.
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PMID:Failure to demonstrate a natriuretic effect of neurophysin in rats. 30 43

The responses of isolated frog skin to 5-hydroxytryptamine (increased active sodium transport and decreased passive chloride permeability) are diminished by incubation with the enzymes neuraminidase and N-acetylneuraminic acid aldolase but only in the absence of Ca2+ and presence of EDTA. The responses induced by oxytocin, adrenalin and aldosterone are unaffected by enzyme treatment.
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PMID:Selective destruction of 5-hydroxytryptamine receptors by neuraminidase. 31 8

Experimental studies relating to the direct peripheral vascular actions of neurohypophyseal hormones and their synthetic variants are reviewed. In addition, the available data on the comparative pharmacologic actions of these peptides on mammalian vascular smooth muscle are reviewed. Experiments relating to mechanisms by which neurohypophyseal peptides induce contraction of blood vessels are discussed. Neurohypophyseal peptide hormones appear to be able to contract and relax vascular smooth muscle, the exact type of response being dependent on species, vascular bed, and region within a vascular bed. Receptors that subserve both contraction and relaxation may exist on different blood vessels within a species, with a preponderance of receptors that subserve contraction being present in most blood vessels. Concentrations of vasopressin that can be considered physiologic (i.e., 10(-13) to 10(-11) M) are capable of evoking responses on a variety of microscopic as well as large blood vessels. Arginine-vasopressin appears to be, relatively, the most potent contractile substance on rat blood vessels investigated to date; angiotensin is not. Preservative-free oxytocin is a contractile agent on all mammalian arterial and arteriolar vessels so far investigated. A great deal of the controversy surrounding the exact vascular actions elicited by these peptide hormones can be attributed to many factors that were not controlled in older experiments. Moreover, rat pressor assays cannot be utilized to determine structure-activity relationship for neurohypophyseal peptides on vascular smooth muscles. Nuerohypophyseal peptide-induced contractions of vascular smooth muscles can be markedly affected by sex, sex hormones, alcohols, [Ca2+]0, [mg2+]0, oxygen deficit, and glucose-deprivation. Extracellular sodium and potassium ions appear to play relatively little role in vasopressin-induced contractions of rat arterial smooth muscle. The terminal amino group, phenolic hydroxyl, aromatic ring and basicity in positions 1, 2, 3, and 8, respectively, of the neurohypophyseal hormones are important for optimizing hormone-receptor affinity and intrinsic contractile activity on vascular smooth muscle. Basicity in position 8 of these peptide hormones is not an absolute requirement for contractile activation of these smooth muscles. Alterations in molecular structure can result in neurohypophyseal peptides with unique, and selective, microcirculatory effects that may be beneficial in the treatment of low-flow states.
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PMID:Vascular smooth muscle and neurohypophyseal hormones. 32 65

The effect of the treatment was controlled by measurements of plasma renin activity and aldosterone concentration. These observations concern maternal toxemia treated by diuretic and dietary sodium restriction two weeks before delivery. In two cases, labor was augmented with oxytocin infusion. These cases illustrate the respective role of sodium depletion and hemodilution in the occurrence of maternal and neonatal hyponatremia. They emphasize the amount of sodium supplementation in these newborn infants.
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PMID:[Neonatal hyponatremia from maternal origin. Three cases (author's transl)]. 40 18


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