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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hydrops allantois was diagnosed in two Haflinger mares with severe abdominal distension. Both mares were seven months pregnant. Abortion was induced with two injections of prostaglandin six hours apart followed by further manual dilation of the cervix and administration of oxytocin the next day. There were 90 and 95 litres of fluid, respectively, in the allantoic cavities which resembled extracellular fluid with regard to concentrations of urea, creatinine, sodium, potassium, calcium, magnesium, phosphate and chloride, but not total protein. Both fetuses had severe brain abnormalities which were diagnosed as cerebellar and cerebral hypoplasia associated with bilateral hydrocephalus internus and hydranencephaly and cerebellar aplasia, respectively. Both mares were pregnant by the same stallion, but a clear hereditary link was not found.
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PMID:Two related cases of cerebellar abnormality in equine fetuses associated with hydrops of fetal membranes. 320 93

Ionic mechanisms of hyperpolarization induced by oxytocin application on the neuronal membrane of identified neurons of Helix pomatia have been studied under voltage clamp conditions. There are two types of neurons and two types of hyperpolarization, respectively. Hyperpolarization of the first type is due to a decrease in chloride permeability and hyperpolarization of the second type is due to an increase in potassium permeability of the surface neuronal membrane. The reversion potential in the first case was -40 mV and decreased with addition of external solutions of furosemide or tolbutamide. The reversion potential in the second case was -70 mV, and with a 2-fold increase of external potassium concentration it shifted towards depolarization by 15 mV, while tolbutamide addition to the external solution induced no changes. It is supposed that Helix pomatia neurons have different receptors to oxytocin. Activation of some receptors causes a decrease in the membrane permeability for chloride ions, probably, through the system of cyclic nucleotides, while activation of their receptors increases potassium permeability of the surface membrane.
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PMID:[Effect of application of oxytocin on neurons of Helix pomatia: hyperpolarization effects]. 321 Dec 31

Increasing concentrations of nicardipine were found to inhibit various types of muscular activation (electrical stimulation, acetylcholine, oxytocin, potassium chloride), as well as the spontaneous rhythmic activity of the isolated rat uterus. The degree of the inhibitory effect of nicardipine depends on the type of activation. Nicardipine showed an exceptionally high efficacy in inhibiting contractions induced by electrical stimulation and of spontaneous rhythmic activity. For inhibition of these contractions, even femtomolar concentrations of nicardipine were sufficient. The relaxant effect of nicardipine depends on the concentration of extracellular calcium and the temperature of the medium. Nicardipine shows high selectivity for the uterine smooth muscle because even in very high concentrations it exerts an insignificant relaxation of the other isolated smooth muscles (oesophagus, bladder, colon descendens) as well as of the isolated intercostal muscle of the rat. Our experiments indicate that nicardipine might have a role in the therapy of premature delivery and abortion because of its great selectivity for the uterine smooth muscle. Nicardipine causes a stronger inhibition of the tonic than of the phasic component of contraction induced by potassium chloride and oxytocin. These findings suggest that potassium chloride and oxytocin act through various populations of calcium channels.
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PMID:Effect of nicardipine on the isolated uterus and other smooth muscles of the rat. 324 44

16 alpha-Hydroxy-ent-kauran-19-oic acid was isolated from Montanoa hibiscifolia. The effects of this acid and its methyl ester on the contractile activity of rat and guinea pig uterine horns were studied. Both inhibited spontaneous, oxytocin-induced and potassium-induced contractile activities. The inhibitory effect produced by the methyl ester was greater than that observed with the acid. The methyl ester was 2-5 times more potent than the acid upon spontaneous and potassium-induced contractions and 11-15 times more potent than the acid upon the contractile activity of uterine smooth muscle induced by oxytocin. Such effects were observed using bath concentrations of 6, 15, 30 and 60 microM of each compound.
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PMID:The zoapatle. XV. Activity of 16 alpha-hydroxy-ent-kauran-19-oic acid isolated from Montanoa hibiscifolia, and its methyl ester on rat and guinea pig uterus. 325 83

1. The concentration of serum albumin in rat milk, rat serum, the stomach contents of suckling rats and mammary homogenates has been measured. 2. Serum albumin in expressed milk ranges in concentration between 3.5 and 6 mg/ml and amounts to an average of 4-5 mg/100 mg total protein whereas, in the stomach contents of suckling rats, serum albumin was 3.2 mg/100 mg total protein. 3. Corresponding concentrations of a second soluble milk protein, alpha-lactalbumin, were 2.9 mg/100 mg total protein in the milk and 1.2 mg/100 mg total protein in the stomach contents. 4. Serum albumin is a major protein in mammary homogenates at 10 mg/100 mg total soluble protein and the calculated total mammary pool of albumin amounts to 110 mg/rat. 5. There was a significant negative correlation between the serum albumin concentration and the ratio of potassium to sodium ions in milk samples obtained from rats milked with varying oxytocin treatments. 6. No evidence for albumin mRNA could be detected when mammary total RNA was probed with a complementary DNA (cDNA) for rat albumin. 7. The data are consistent with albumin being a major whey protein in the rat, it being synthesized at an extramammary site and transferred to the milk space by a paracellular mechanism from an extravascular mammary pool rather than directly from the serum.
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PMID:Serum albumin secretion in rat milk. 344 53

Rat neurointermediate lobes and neurohypophyses separated from the pars intermedia were stimulated in vitro in the presence of either D-Ala2, D-Leu5-enkephalin (DADLE), a Leu-enkephalin stable analogue or FK 33-824 a Met-enkephalin stable analogue. Secretion of vasopressin (AVP) and oxytocin (OT) was produced by either a Ca2+-ionophore or with electrical stimulation or by K+-induced depolarization. These opioid peptides and their antagonist naloxone did not affect basal nor evoked hormone release. Furthermore, they did not affect the evoked calcium uptake induced with electrical stimulation. These findings were confirmed using a preparation of isolated neurosecretory nerve endings. Further, dopamine had no effect on the K+-induced AVP release although a crude extract of the pars intermedia abolished the electrically-evoked and reduced considerably the potassium-evoked AVP release. It is concluded that in the neurohypophysis neither Leu- and Met-enkephalin nor dopamine affect the secretion-coupling mechanism at the level of the neurosecretory nerve endings.
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PMID:Do opioid peptides modulate, at the level of the nerve endings, the release of neurohypophysial hormones? 351 53

Distribution of Ca2+ ions, precipitated by means of pyroantimonate potassium, has been investigated electron microscopically in secretory cells of the mammary gland of lactating white mice. In the glandular cells, that are at the state of inhibition of secretory activity, the cytochemical reaction product is localized on the internal side of the basal, lateral and apical parts of the plasmolemma, in mitochondrial matrix, in cisterns and in the Golgi complex vesicles, in the nuclear areas, occupied by euchromatin. Oxytocin effect produces a certain complex of ultrastructural changes in the cell accompanied by redistribution of Ca2+ ions. Amount of precipitate in mitochondria decreases. It is revealed in the lumen of dilated canals of the granular endoplasmic reticulum, in the zone of decondensated nuclear chromatin, in the Golgi complex vesicles. The vesicles become larger and fuse with each other. The changes mentioned demonstrate increased synthetic and transport processes, occurring in the glandular epithelium of the mammary gland after oxytocin effect.
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PMID:[Localization of calcium in the secretory cells of the mammary glands in response to oxytocin]. 356 41

A possible involvement of oxytocin (OT) has been indicated in regulation of water and electrolyte metabolism, based on findings that the secretion of OT is increased by either water deprivation or sodium loading. However, to date, no informations have yet been obtained about the role of OT in hypertension. The present study was therefore undertaken to elucidate the role of OT for abnormalities of fluid and electrolyte metabolism in essential hypertension (EH) in comparison with normotensive subjects (NT). The major results were as follows. Plasma level of OT was 3.7 +/- 2.1 pg/ml (mean +/- SD) in EH, not significantly higher than that in NT (3.2 +/- 1.7 pg/ml). Plasma OT in low-renin EH (4.8 +/- 2.5 pg/ml) was significantly different from that in high-renin EH (2.9 +/- 1.4 pg/ml, p less than 0.05) and NT (p less than 0.05), but not in normal-renin EH (3.8 +/- 2.0 pg/ml). Plasma OT was inversely correlated with plasma renin activity (PRA) in EH (r = -0.384, p less than 0.01), but not in NT (r = 0.102). No significant correlation was found between plasma OT and plasma aldosterone concentration (PAC), plasma concentration of antidiuretic hormone (ADH), serum sodium and potassium, blood pressure and renal function in either EH or NT. I.m. injection of OT (0.04 IU/kg) increased significantly urinary excretions of sodium and potassium in EH and NT. However, the increment in sodium excretion was greater in low-renin EH than that in normal-renin EH (0.05 less than p less than 0.10), high-renin EH (p less than 0.05) and NT (p less than 0.05). PRA, PAC and ADH were significantly decreased after OT injection, but blood pressure, serum sodium and potassium were not altered in both EH and NT. I.v. administration of OT (0.1 approximately 0.2 IU/min) suppressed angiotensin II-induced increase of PAC and elevation of blood pressure in both EH and NT. The decrease in PAC by the OT administration was the greatest in low-renin EH. The reduction of blood pressure was significantly greater in EH than in NT (p less than 0.05). I.v. administration of hypertonic saline (5%) resulted in a significant increase of plasma OT in EH and NT, and the increment in OT was the greatest in low-renin EH. Serum sodium concentration was increased by the infusion, positively correlated with plasma OT in both EH (r = 0.458, p less than 0.05) and NT (r = 0.830, p less than 0.05).(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:[Significance of oxytocin to disorders of fluid and electrolyte metabolism in patients with essential hypertension]. 356 5

The interchange reaction of disulfides was caused by the copper(II)/ascorbic acid/O2 system. The incubation of two symmetric disulfides, L-cystinyl-bis-L-phenylalanine (PP) and L-cystinyl-bis-L-tyrosine (TT), with L-ascorbic acid and CuSO4 in potassium phosphate buffer (pH 7.2, 50 mM) resulted in the formation of an asymmetric disulfide, L-cystinyl-L-phenylalanine-L-tyrosine (PT), and the final ratio of PP:PT:TT was 1:2:1. As the reaction was inhibited by catalase and DMSO only at the initial time, hydroxyl radical generated by the copper(II)/ascorbic acid/O2 system seemed to be responsible for the initiation of the reaction. Oxytocin and insulin were denatured by this system, and catalase and DMSO similarly inhibited these denaturations. As the composition of amino acids was unchanged after the reaction, hydroxyl radical was thought to cause the cleavage and/or interchange reaction of disulfides to denature the peptides.
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PMID:Interchange reaction of disulfides and denaturation of oxytocin by copper(II)/ascorbic acid/O2 system. 359 55

We examined the renal effects of synthetic oxytocin (OT) in the presence and absence of vasopressin in conscious euvolemic rats. Both sexes of the Long-Evans (LE) and Brattleboro homozygous (DI) strains were used. OT infused intravenously at 0.25 and 2.5 ng X min-1 X 100 g body wt (BW)-1 resulted, respectively, in plasma concentrations of 30 +/- 6 and 265 +/- 88 pg/ml in LE rats and 46 +/- 5 and 327 +/- 29 pg/ml in DI rats. Glomerular filtration rate (GFR) was augmented most consistently by the larger dose of hormone in LE rats (P less than 0.05), whereas the low infusion rate of OT enhanced GFR in DI rats (P less than 0.01). Effective renal plasma flow was not changed significantly. OT (both doses) increased the fractional excretion of sodium two- to threefold in each strain of animal (all at least P less than 0.05 from control), whereas the fractional excretion of potassium was largely unaffected. In LE rats, a diuresis was observed with either infusion rate of hormone, accompanied by a rise in osmolar clearance (COsm). In contrast, there was no change of urine flow with the low dose of OT in DI rats, because COsm increased and the clearance of free water (CH2O) decreased proportionately. The higher infusion rate of OT promoted antidiuresis in DI rats, with negative CH2O and little change in COsm. We conclude that oxytocin enhances GFR and is natriuretic regardless of the presence or absence of endogenous vasopressin.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Influence of oxytocin on renal hemodynamics and electrolyte and water excretion. 374 Feb 76


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