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)

During water diuresis in anesthetized rats, 4-leucine-oxytocin increased the urine output and the rates of sodium and chloride excretion. The potassium excretion rate was only slightly increased. During vasopressin-suppressed water diuresis, 4-leucine-oxytocin produced similar effects on urine and electrolyte excretions. In addition, it inhibited the vasopressin-induced free-water reabsorption, and it could reverse reabsorption to freewater clearance.
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PMID:4-Leucine-oxytocin: natriuretic, diuretic, and antivasopressin polypeptide. 565 33

1. The rate of release of neurohypophysial hormones in vitro, using isolated, halved neural lobes of the rat in an incubation medium containing excess K(+) and Ca(2+), was measured. The highest average rate of release was observed between 10 and 20 min after commencement of incubation.2. Incubation of isolated, halved rat neural lobes in the presence of acetylcholine, with or without eserine, did not stimulate hormone release. When complete isolated hypothalamo-neurohypophysial systems were incubated in a suspension medium containing 10(-7) mg/ml. acetylcholine a significant increase in the release of oxytocin occurred (P < 0.01); the increase in vasopressin release was less pronounced (P < 0.05).3. Uptake of O(2) by the isolated, halved neural lobes and the hypothalamo-neurohypophysial systems continued for 2-3 hr, i.e. in excess of the experimental incubation time.4. During the first 40 min of incubation the control halved neural lobes increased in weight; the neural lobes incubated in buffer containing high potassium and calcium showed no increase in weight.5. Neural lobes incubated in buffer containing excess K(+) and Ca(2+) contained about 3 times as much potassium as controls. The sodium content was not affected significantly.6. Factors involved in the process of neurohypophysial hormone release are discussed.
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PMID:Release of neurohypophysial hormones in vitro. 603 18

The effects of chlorbutol (0.7, 1.4 and 2.8 mM) on the contractile responses induced by KCl and noradrenaline (NA) and on 45Ca movements have been studied on rat isolated thoracic aorta. Chlorbutol decreased, in a dose-dependent manner, contractions induced by KCl and NA and this effect was observed whether it was added before or after the induced contractions. Preincubation with chlorbutol inhibited the contractile responses elicited by addition of Ca (1-5 mM) to Ca-free high-potassium solution. It also inhibited in a dose-dependent manner the 45Ca influx but increased 45Ca efflux in rat aortic strips. These results suggest that chlorbutol decreases peripheral resistance by reducing the availability of intracellular Ca to the contractile machinery in vascular smooth muscle cells. The effects of synthetic oxytocin (Syntocinon) at concentrations containing the same chlorbutol concentration were quantitatively similar from those produced by chlorbutol alone. Therefore, the inhibitory cardiovascular effects ascribed previously to synthetic oxytocin may be attributed to its preservative, chlorbutol, and not to oxytocin itself.
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PMID:Effects of chlorbutol on 45Ca movements and contractile responses of rat aorta and its relevance to the actions of Syntocinon. 614 94

Rat pituitary neural lobe contained high concentrations of cholecystokinin-like immunoreactivity (CCK-LI). Section of the pituitary stalk resulted in loss of CCK-LI, and both lactation and replacement of drinking water with 2% saline resulted in marked depletion of CCK-LI. Rats with congenital diabetes insipidus (Brattleboro strain) had a 73% reduction in CCK-LI below the levels of hooded Long-Evans controls, where as levels in the brain were unchanged. Release of CCK-LI, labeled dopamine, and gamma-amino butyric acid in response to potassium depolarization was studied. There was a low fractional release of CCK-LI. Addition of sulfated CCK-8 (CCK-8s) to the medium enhanced the calcium-dependent potassium-stimulated release of dopamine, but basal release was unaffected. gamma-Amino butyric acid release was only poorly calcium dependent and not effected by extracellular CCK-8s. Vasopressin and oxytocin release were stimulated by electrical stimulation of the pituitary stalk, and were unaffected by the addition of CCK-8s to the medium. In vivo, however, the injection of 5 micrograms CCK-8s into the third ventricle resulted in increased plasma vasopressin concentrations.
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PMID:Localization and actions of cholecystokinin in the rat pituitary neurointermediate lobe. 632 36

Brattleboro (diabetes insipidus) rats showed a delayed recovery from 6-hydroxydopamine (6-OHDA) hypotension as compared to Long Evans controls. A slight increase in circulating arginine vasopressin was noted in the 6-OHDA-treated Long Evans rats but no change in circulating oxytocin was apparent in either species. The haematocrit and plasma potassium suggested haemodilution in Long Evans rats following 6-OHDA treatment but no such changes were apparent in similarly treated Brattleboro rats. Since the major difference in Long Evans and Brattleboro rats is the latter's inability to synthesize arginine vasopressin (AVP), it is suggested that AVP may have a role in the restoration of homeostasis following 6-OHDA-induced hypotension. This conclusion is supported by (a) a delayed recovery from hypotension and (b) no change in blood concentration parameters, in the Brattleboro rat.
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PMID:Reversal of 6-hydroxydopamine-induced hypotension in Long Evans and diabetes insipidus (Brattleboro) rats. 640 2

The status of the mare and foetus in relation to readiness for birth was assessed by measurement of the electrolytes sodium, potassium and calcium in mammary secretions pre-partum. Sixteen Thoroughbred mares were allowed to foal spontaneously and the ionic status of their mammary secretions was measured over three to five weeks pre-partum. From these measurements, a scoring system was developed where an ionic score of 35 points or more suggested that the mare was within 24 h of foaling. On the basis of this ionic score, 10 pony mares were induced with either oxytocin or fluprostenol and assessment of foal maturity was made by physical, behavioural and physiological criteria. Eight pony mares, induced when the ionic score was 35 points or more, delivered full term foals; two mares were induced when their scores were 30 and 20 points and delivered a full term and slightly immature foal respectively. These results suggest that foetal maturity may be related to electrolyte concentrations in mammary secretions and that an ionic score of 35 points or more may indicate that induction would be successful in terms of maturity of the newborn foal.
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PMID:Preliminary studies of mammary secretions in the mare to assess foetal readiness for birth. 647 23

Infusions of Phyllanthus sellowianus or P. niruri (Euphorbiaceae) are a popular remedy in Brazil for kidney and bladder stones. This study describes the isolation of an alkaloid from P. sellowianus, denoted ALK-1, and compares its antipasmodic activity with that of papaverine on isolated strips of guinea pig ileum and rat uterus, and rat aorta rings. ALK-1 and papaverine promoted a dose-dependent flattening of the dose-response curves obtained to acetylcholine and histamine on ileum strips and of the dose-response curves to acetylcholine and oxytocin on uterine strips. A non-competitive antagonism of noradrenaline-induced contractions by the P. sellowianus alkaloid was also demonstrated on aortic rings. Whereas the antispasmodic potency (pD'2 values) of papaverine did not depend on the muscle preparation and agonist used, ALK-1 exhibited a greater potency on the ileum strips than on the uterine or aortic preparations. Because of this selective antispasmodic action on the ileum, ALK-1 was equipotent to papaverine on this tissue, but was about 10-fold less potent than papaverine on uterine smooth-muscle. The dose-response curves to CaCl2 obtained for potassium-depolarized uterine strips were shifted to the right by both antispasmodics. Similar pA2 values with slopes not differing from unity -1.0 were obtained from Schild plots of the data, suggesting that competitive antagonism of calcium entry into the cell is a mechanism of action common to both alkaloids. The presence of at least one potent antispasmodic alkaloid in P. sellowianus justifies the popular use of infusions of this plant. Smooth muscle relaxation within the urinary or biliary tract probably facilitates the expulsion of kidney or bladder calculi.
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PMID:Antispasmodic effects of an alkaloid extracted from Phyllanthus sellowianus: a comparative study with papaverine. 652 14

The effects of nicardipine, a calcium-entry blocker which also has a potent phosphodiesterase inhibitory action, were investigated on isolated human term-pregnant and nonpregnant myometrium, and compared with those of nifedipine. Both drugs relaxed pregnant and nonpregnant myometrial preparations contracted by potassium (127 mM), and also reduced or abolished contractions occurring spontaneously, or induced by prostaglandin F2 alpha, oxytocin and vasopressin. However, the effect of nicardipine had a slower onset of action than that of nifedipine, and the drug was significantly more potent than nifedipine is at least as effective as nifedipine. If the differences between the drugs can be reproduced also in vivo, nicardipine offers an interesting alternative to nifedipine for inhibition of undesired uterine activity.
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PMID:Comparison of the effects of nicardipine and nifedipine on isolated human myometrium. 658 Nov 15

The effects of high potassium, carbachol and oxytocin on 40Ca-45Ca exchange in the estradiol-treated rat uterine longitudinal muscle were compared with those in the ovariectomized one using the modified "Lanthanum Method." The treatment of estrogenized or ovariectomized myometrium with 60 mM K+ significantly increased the 45Ca space at 5-, 10-, 30- and 60-min incubation times. The increase in the 45Ca by high-K+ in the estrogenized myometrium was much greater than that in the ovariectomized one. Carbachol (2 X 10(-6) M) had little influence on the 45Ca space at all incubation periods with the exception of the 10-min one in both uteri. The higher concentration of carbachol (2 X 10(-4) M) in the estrogenized myometrium produced a marked increase in the 45Ca space after the 10-min incubation, while in the ovariectomized uterus, a slight increase in the 45Ca space was observed at the 10- and 30-min incubation times. The increase in the 45Ca space by 2 X 10(-4) M carbachol in the estrogenized myometrium was greater than that in the ovariectomized one. Oxytocin (10(-4) and 10(-3) units/ml) increased the 45Ca space at and after the 10-min incubation times in the estrogenized uterus, while in the ovariectomized uterus, oxytocin (10(-3) and 10(-2) units/ml) showed little influence on the increase in the 45Ca space. The increase in 45Ca space by carbachol and oxytocin was inhibited by papaverine. These results suggest that differences in dependence upon Ca2+ in the medium may exist in contractions induced by high-K+, carbachol and oxytocin in the uterine smooth muscle and that the contractions in the estradiol-treated myometrium may be more dependent upon extracellular Ca2+ than those in the ovariectomized one.
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PMID:Effects of high potassium depolarization, carbachol and oxytocin on the Lanthanum-resistant 45Ca fraction in rat myometrium. 687 8

The effect of intense muscular work (80% of maximal oxygen uptake) on responses of plasma hormones involved in electrolyte and water balance were measured in 14 male subjects. They were divided into three groups according to their maximal oxygen uptake and the duration of exercise performed until exhaustion: well trained subjects (group I), trained subjects (group II), and untrained subjects (group III). Pulmonary gas exchange, heart rate, rectal and skin temperature, and weight loss were measured as well as hematocrit and plasma and urine sodium and potassium concentrations. Rectal temperature increased significantly in all subjects after exhaustion. The variation of hematocrit was smallest and the weight loss greatest in the well-trained subjects. Plasma aldosterone, renin activity (PRA), vasopressin (AVP), and neurophysin (Np) displayed highly significant increases after exercise in all three groups: PRA was increased 4.5 times (p < 0.01), aldosterone 13 times (p < 0.05), Np 2.6 times (p pe 0.05), and AVP 4.8 times (p < 0.05). Nevertheless, there was no correlation between the changes in PRA and those in plasma aldosterone, nor between aldosterone and plasma sodium or potassium. At the urinary level, the only striking observation was that free water clearance tends to become positive after exercise. Our results provide evidence that this kind of exercise produces a highly significant increase in plasma levels of the hormones involved in electrolyte and water balance. They also indicate that it is among the well-trained subjects that sweat loss is highest though the hematocrit increase is the smallest; this suggests that water is shifted more efficiently from the extravascular compartment.
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PMID:Plasma AVP, neurophysin, renin activity, and aldosterone during submaximal exercise performed until exhaustion in trained and untrained men. 699 37


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