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

The authors studied the dynamics of natural substrates of neurohumoral origin (oxytocin and lysine-vasopressin) by the serum of pregnant and nonpregnant women in relation to the pH in the medium, within pH limits of 2.5 to 8. The values obtained in a polarographic study of depression of the complex oxytocin and lysine-vasopressin polarographic wave by pregnancy and non-pregnancy sera and the results of a parallel analysis of free amino acids of the inactivated substrates under the same conditions showed that, apart from deep degradation of the studied substrates at the optimum pH (5.5 minus 8), less pronounced degradation of the molecule at low pH values (3 minus 4,5), i.e. in a non-physiological blood medium, also occurred. On the basis of their results, the authors submit the hypothesis of the existence of oxytocinase isoenzymes and of the probable presence of several peptidases with overlapping specificity.
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PMID:The influence of pH in the medium on degradation of neurohormones by pregnancy serum. 23 51

1 Synthetic analogues of oxytocin and of lysine-vasopressin with an hydroxyl group in either the L ro D configuration replacing the primary amino group have been tested for biological activity.2 [1-(L-2-Hydroxy-3-mercaptopropanoic acid)] oxytocin ([L-Hmp(1)]oxytocin) was 1.5 to 2 times more potent than oxytocin on the rat uterus in situ, the rat mammary strip and the rat mammary gland in situ and 3 times more potent on the rat isolated uterus.3 The pressor activity of [1-(L-2-hydroxy-3-mercaptopropanoic acid)-8-lysine]vasopressin ([L-Hmp(1), Lys(8)] vasopressin) was 2.2 and the antidiuretic activity 2.1 times that of lysine-vasopressin.4 The [D-Hmp(1)] analogues of oxytocin and vasopressin were much less potent than the [L-Hmp(1)] analogues.5 The responses to oxytocin and its hydroxy analogues in vivo were qualitatively indistinguishable but the pressor and antidiuretic responses to the hydroxy analogues of lysine-vasopressin were prolonged compared with those to the parent hormone.6 The hydroxy analogues of oxytocin and lysine-vasopressin were not inactivated by pregnancy plasma oxytocinase.7 The results are discussed in relation to the importance of the primary amino group for the biological activity and metabolism of the neurohypophysial hormones.
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PMID:Hydroxy analogues of oxytocin and of lysine-vasopressin. 51 8

A vasopressin substrate radioimmunoassay (RIA) system is described for the measurement of the vasopressinase elaborated during pregnancy. Results show that vasopressinase activity increases in the sera of pregnant women throughout gestation. At term, under the in vitro conditions described, pregnancy serum degrades vasopressin (Pitressin) at a rate of 53 mU. per milliliter of serum per minute. Serum obtained from paired umbilical cord samples had an activity of 9.2 muU per milliliter per minute; amniotic fluid obtained at delivery had an activity of 16.6 muU per milliliter per minute. Pregnancy serum obtained from sheep, rabbits, and rats, ovine umbilical cord serum, and ovine amniotic fluid had no detectable vasopressinase activity. Normal human male serum, nonpregnant female serum, and serum from women taking contraceptive agents also exhibited no activity.
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PMID:The circulating vasopressinase of pregnancy: species comparison with radioimmunoassay. 111 45

1. Bothrops jararaca plasma or serum hydrolysed L-cystine-di-beta-naphthylamide (CNAse activity) at a degree comparable to that of plasma or serum in pregnant women. 2. In adult snakes, activity was less in males. It was not altered in pregnancy but increased after delivery, being higher at pH 6.4 (unspecific enzymes) than at pH 7.9 (true pregnant woman plasma oxytocinase). 3. Its optimum pH was 5.9, different from that of other known enzymes that hydrolyse the same substrate. 4. Bothrops jararaca plasma also hydrolysed vasopressin, oxytocin and vasotocin. 5. These hydrolysing activities were unexpected for an ovoviviparous reptile.
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PMID:Hydrolysis of L-cystine-di-beta-naphthylamide and neurohypophyseal peptides by the plasma of the snake Bothrops jararaca. 152 15

Human placental leucine aminopeptidase (P-LAP) was purified from retroplacental serum for the first time by serial chromatography on columns of Matrex Blue A, DEAE-Sepharose CL-6B, phenyl-Sepharose 4B, chelating-Sepharose, and Sepharose CL-6B. The purified P-LAP was apparently homogeneous on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and the apparent molecular weight (Mr) was estimated to be 210,000. By comparing P-LAP activity with cystine aminopeptidase activity, we concluded that both activities were shared by the same molecule. We also examined the hydrolytic activity of P-LAP using naturally occurring peptide hormones and found that the enzyme hydrolyzed oxytocin, vasopressin, and angiotensin III. These results suggest that P-LAP shows oxytocinase activity and plays an important role in the regulation of the plasma level of these hormones during pregnancy.
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PMID:Identification of human placental leucine aminopeptidase as oxytocinase. 173 8

This article, a review of factors controlling vasopressin (AVP) release in pregnancy, extends our contribution to a symposium in this journal published in 1987 (vol X, pp 270-275). Body tonicity decreases (approximately 10 mOsm/kg) very early in pregnancy due to decrements in the osmotic thresholds for AVP release and thirst. In addition, the metabolic clearance rate (MCR) of AVP markedly increases between gestational week 10 and midpregnancy, and is paralleled by the appearance and increase of circulating cystine aminopeptidase (vasopressinase), while the MCR of 1-deamino-8-D-AVP (DDAVP), an analogue resistant to inactivation by the enzyme, changes little in pregnancy. These increases (MCR of AVP and plasma vasopressinase) may explain certain syndromes of transient diabetes insipidus (DI) that complicate gestation. Finally, mechanisms responsible for the altered osmoregulation in pregnancy are obscure, but chorionic gonadotropin may be involved in the changes during human gestation.
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PMID:Osmotic and volume control of vasopressin release in pregnancy. 199 49

Preeclampsia is characterized by increased vascular sensitivity to Angiotensin II, endothelial damage, and arteriolar spasm. We hypothesize that these events may be initiated by stimulation of V1 receptors. V1 receptors are normally activated by vasopressin. However, V1 receptors may be activated by the nonapeptide formed when vasopressin is metabolized by the placental enzyme--vasopressinase. This enzyme, found only in humans, cleaves the ring structure of vasopressin, but leaves the N-terminal end, the locus of pressor activity, intact. The resulting molecule, vasopressinase altered vasopressin (VAV), may be present in greater concentration in preeclamptic women and over the months of the second trimester initiate the cascade of pathophysiologic changes resulting in toxemia.
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PMID:A proposed relationship between vasopressinase altered vasopressin and preeclampsia. 219 37

Osmoregulation is altered in human gestation, body tonicity declining to a nadir early in pregnancy after which a new steady-state plasma osmolality is maintained until term. Development of precise, sensitive, and specific radioimmunoassays for arginine vasopressin (AVP), which permit clearer definitions of functional properties of the osmoregulatory system, have led to a formulation of how these changes occur (both in women as well as in a gravid rat model). The osmotic thresholds for thirst and antidiuretic hormone release each decrease approximately 10 mosmol/kg during the initial weeks of human gestation. Lowering the threshold to drink stimulates increased water intake and dilution of body fluids. Because AVP release is not suppressed at the usual levels of tonicity, it still circulates and water is retained. Osmolality declines until it decreases below the osmotic thirst threshold (situated several mosmol/kg above that for hormone secretion), and a new steady state, with little change in water turnover, is established. The metabolic clearance rate of AVP is also altered, increasing three- to fourfold between gestational week 10 and midtrimester, paralleling the appearance and rapid rise in circulating cystine-aminopeptidase (vasopressinase), an observation that may explain several disorders of water handling that complicate human pregnancy. Finally, mechanisms responsible for the altered osmoregulation are obscure but chorionic gonadotropin may be involved in the changes during human gestation.
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PMID:Osmoregulation of thirst and vasopressin release in pregnancy. 266 25

A young patient developed hypothalamic diabetes insipidus due to histiocytosis in infancy and was satisfactorily treated with Pitressin. As a teenager she no longer had thirst or polyuria after treatment was stopped. These symptoms only returned during her two pregnancies. When non-pregnant her urine output was 1.7-2.0 1/24 h, basal plasma osmolality 288-290 mOsm/kg, and during pregnancy 24 h urine volume was 4.5-5.21, plasma osmolality 278-280 mOsm/kg. Studies on osmoregulation of thirst and AVP release, and on renal sensitivity to the V2 agonist desmopressin and endogenous vasopressin were performed in pregnant and non-pregnant states. She had no circulating antibodies to AVP, and the effect of pregnancy-associated vasopressinase was eliminated. Results showed lowered basal plasma osmolality and osmolar thirst threshold in pregnancy but no failure of the renal concentrating mechanism. Plasma AVP concentrations after osmotic stimulation were lower in pregnancy. We propose that she developed thirst and polyuria during pregnancy because of lowering of her osmolar thirst threshold to plasma osmolalities which caused her to drink sufficient quantities of fluid to further reduce AVP secretion. We cannot exclude, however, the possibility that there was increased clearance of circulating AVP.
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PMID:Recurrent pregnancy-induced polyuria and thirst due to hypothalamic diabetes insipidus: an investigation into possible mechanisms responsible for polyuria. 374 36

Aminopeptidase from dysgerminoma was purified and characterized using L-leucine-beta-naphthylamide as substrate. The enzyme was resistant to puromycin, methionine, amastatin, bastatin, and EDTA, and it was heat labile at 60 degrees C. The enzyme showed the same electrophoretic mobility as pregnant-patient serum oxytocinase CAP1 on polyacrylamide gel electrophoresis. Km value against S-benzylcysteine-p-nitroanilide was 4.2 X 10(-4) M. Oxytocin and vasopressin competitively inhibited the enzyme activity. Molecular weight of the enzyme was estimated to be 80,000 by Sephadex G-200 column chromatography. These results suggest that aminopeptidase from dysgerminoma is an oxytocinase-like enzyme, a placenta-specific protein.
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PMID:Oxytocinase-like enzyme in an ovarian dysgerminoma: a placenta-specific protein. 408 42


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