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

The successful termination of 19 consecutive late 1st and 2nd trimester pregnancies using a combination of intravenous prostaglandin E2 (PGE2) and oxytocin (Syntocinon) is reported. PGE2 (5 mg in 500 ml of 5% glucose) was initially infused at the rate of 2.5 mcg/minute and then increased to 5 mcg/minute after half an hour. The infusion was increased to a maximum of 10 mcg/minute. Oxytocin was infused 2 hours after the PGE2 at a constant rate of 128 mU/minute. Mean total dose of PGE2 used was 5.9 mg at an overall rate of 6.1 mcg/minute. Average induction/delivery interval was 16 hours, with only 1 patient taking more than 24 hours. Abortion was complete in 13 cases (68%). Vomiting occurred in 13 women; pain was minor and was controlled by pethidine. Mild and transient thrombophlebitis was also reported. There were no reported cases of diarrhea and or cervical damage. Compared to the use of intravenous PG alone, PG given intraamniotically alone or with intravenous oxytocin, and PG given extraamniotically alone or with intravenous oxytocin, this study shows that a combination of intravenous PGE2 and oxytocin at the dose level described is closer to meeting all the desired criteria for the acceptability of any abortion method (ease and safety of administration, side effects, lengths of induction delivery interval, and effectiveness in terms of success rate and uterine evacuation).
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PMID:Letter: Intravenous prostaglandins and oxytocin for mid-trimester abortion. 4 97

The binding of 3H-labelled neurohypophyseal nonapeptide hormone, oxytocin, to isolated rat fat cells has been measured under conditions where this compound elicits the known activation of glucose oxidation by these cells, called "insulin-like" action. Uptake by the cells of the [3H]peptide as a function of various concentrations of the hormone in the medium indicated the presence of two classes of binding sites with different apparent affinities and capacities. The sites of the first type exhibit a rather high affinity, but low capacity, for oxytocin (5 nM; 3 X 10(4) sited per cell) and appear to be saturable under a reversible process. Evaluation of dose-response relationships suggest that they may be directly related to the measured biological response (i.e. activation of the glucose to 14CO2 conversion). Competition experiments show that [3H]oxytocin binding to the cells remains constant within a large range of insulin concentrations. The apparent capacity of different hormone analogs to compete with oxytocin for binding to this class of receptors has been evaluated and compared with the measured insulin-like activity of these different compounds. The sites of the second category have significantly lower affinity, but higher capacity for oxytocin, and were found to be not saturable under the experimental conditions. [3H]Oxytocin uptake by ghosts prepared from the isolated fat cells showed striking similarities to the binding process described for whole cells, although the affinity and total capacity of the former were found to be slightly lower. The basal and adrenalin-stimulated adenylate cyclase of these fractions appeared to be unaffected by various concentrations of oxytocin. It is concluded that there may exist on the rat fat cell membranes a discrete number of oxytocin receptors possessing high specificity for oxytocin and exhibiting affinities and kinetic behaviour similar to those of other characterized oxytocin receptors. They are believed to be independent of the other hormonal receptors of the rat fact cells.
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PMID:Characterization of oxytocin receptors on isolated rat fat cells. 17 Jan 3

Choroid plexus of rabbit and rat was incubated for 2-30 min at 37 degrees C under 95% O2-5% CO2 in Tyrode solution containing 10 mM glucose and 1 mM theophylline with these agents: epinephrine, norepinephrine, isoproterenol, dopamine, histamine, serotonin, arginine, and lysine vasopressins, oxytocin, angiotensin, adrenocorticotropin (ACTH), beta-melanocyte-stimulating hormone, and choroid plexus peptide IIF. After incubation, tissue and medium were analyzed for 3', 5' -cyclic adenosine monophosphate (cAMP) content. Each amine or peptide was tested initially at 1,000 microng/ml. Only ACTH and serotonin affected cAMP content of rabbit choroid plexus. At 1,000 microng/ml, these agents caused a 10 and 4 times (respectively) increase in cAMP content of tissue + medium at 2-10 min with decline in content at 10-30 min. More than 90% of the increment was located in tissue, less than 10% in medium. Minimal effective dose (MED) to cause a significant (P less than .05) accumulation of cAMP was 0.1 microng/ml (2.2 x 10(-8) M) for ACTH and 10 microng/ml (5.7 x10(-3) M) for serotonin. Only isoproterenol, epinephrine, and norepinephrine influenced cAMP content of rat choroid plexus. MED's for this effect by isoproterenol, epinephrine, and norepinephrine were .001, .01, and 10 microng/ml (4.7 x 10(-9), 5.5 x 10(-8), and 5.9 x 10(-5) M), respectively.
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PMID:Effects of hormones on 3', 5' -cyclic adenosine monophosphate in choroid plexus. 19 84

A simple radioreceptor assay for insulin rat liver membranes as receptor sites, with sufficient specificity precision, and sensitivity to detect 10 ng or 276 muU/ml of serum insulin, has been developed. In the presence of standard porcine insulin at the concentration of 1.0 ng/tube, approximately 8% of 125I-porcine insulin was bound to the plasma membranes and ninety-five per cent of this binding was inhibited by 1.0 microgram of standard insulin per tube. Four animal insulins inhibited the binding of 125I-insulin while ACTH, glucagon, human growth hormone, and oxytocin were inert. Insulin values in dog pancreatic vein sera obtained during and after glucose loading and measured by the present radioreceptor assay agreed well with immunoreactive insulin. The ratio of IRI to the measurement by radioreceptor assay was 1.09 +/- 0.18 for the same sera.
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PMID:A radioreceptor assay for insulin: direct measurement of dog pancreatic vein serum insulin. 19 69

Activation of 2-deoxyglucose transport in isolated rat fat cells by insulin is dependent upon the presence of Ca2+ in the external medium. When calcium concentration is kept below 100 micron, insulin acts like a partial agonist, giving only half of the maximal activation obtained normally with a millimolar concentration of this ion. Oxytocin, whose insulin-like action on adipocytes activates glucose oxidation by these cells, was found to be unable to affect the rate of 2-deoxyglucose transport. This, together with previous observations, suggests that calcium ions play a role in the mechanism of insulin action possibly by binding selectively to membrane sites involved in the transmission of the hormonal message to the glucose carrier. Oxytocin seems to trigger only intracellular glucose metabolism and it appears that there is an absolute requirement for calcium ions in the activation of a still unknown membrane signal.
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PMID:Calcium as modulator of the hormonal-receptors-biological-response coupling system. Effects of Ca2+ ions on the insulin activated 2-deoxyglucose transport in rat fat cells. 20 16

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

A report of 2 cases of acute renal insufficiency in african women, 8 months pregnant and suffering of malignant malaria. In both cases labor has been induced by artificial breaking of the membranes and use of oxytocin. One of the children was still-born and the other died 3 days later. Delivery has been followed by a resumption of the urinary flow, facilitated by high dosages of furosemide. This diuretic drug when associated with hypoprotidic diet, hypercaloric intravenous infusions of glucose hypertonic solutions supplemented with amino-acids gives a good chance of recovery without extra-renal dialysis.
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PMID:[Acute renal insufficiency caused by Plasmodium falciparum malaria in the last period of pregnancy (2 cases) (author's transl)]. 36 41

Low doses of arginine-vasotocin (AVT), isotocin and oxytocin (1 pg-1 ng/kg body weight) were antidiuretic in eels adapted to fresh water but not in those adapted to sea-water. High doses (more than 10 ng/kg) were always diuretic. No effects on tubular water reabsorption were observed and the glomerular filtration rate (GFR) was proportional to the maximum reabsorptive rate for glucose (Tm(glucose)) in eels adapted to sea-water. Increases in urinary flow appeared therefore to result from glomerular recruitment. Infusion of AVT or isotocin at low rates reduced the GFR and urinary flow of freshwater eels to the levels found in seawater eels. Vasopressin (lysine or arginine) had no direct effect on kidney function in freshwater eels but blocked both the diuretic and antidiuretic actions of the other hormones. When infused into seawater eels it was diuretic. This effect could have been due to blockade of the actions of endogenous AVT and/or isotocin.
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PMID:Neurohypophysial hormonal control of kidney function in the Furopean eel (Anguilla anguilla L.) adapted to sea-water or fresh water. 62 24

1. The hormonal control of glycogen breakdown was studied in hepatocytes isolated from livers of fed rats. 2. Glucose release was stimulated by [8-arginine]vasopressin (10pm-10nm), oxytocin (1nm-1mum), and angiotensin II (1nm-0.1mum). These responses are all at least as sensitive to hormone as is glucose output in the perfused rat liver. 3. The effect of these three hormones on glucose release was critically dependent on extracellular Ca(2+), unlike that of glucagon. Half-maximal restoration of the vasopressin response occurred if 0.3mm-Ca(2+) was added back to the incubation medium. 4. Glycogen breakdown was more than sufficient to account for the glucose released into the medium, in the absence or presence of hormones. Lactate release by hepatocytes was not affected by vasopressin, but was inhibited by glucagon. 5. If Ca(2+) was omitted from the extracellular medium, vasopressin stimulated glycogenolysis, but not glucose release. 6. The phosphorylase a content of hepatocytes was increased by vasopressin, oxytocin and angiotensin II; minimum effective concentrations were 0.1pm, 0.1nm and 10pm respectively. This response was also dependent on Ca(2+). 7. These results demonstrate that hepatocytes can respond to low concentrations of vasopressin and angiotensin II, i.e. these effects are likely to be relevant in the intact animal. The role of extracellular Ca(2+) in the effects of these hormones on hepatic glycogenolysis and glucose release is discussed.
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PMID:Rapid stimulation by vasopressin, oxytocin and angiotensin II of glycogen degradation in hepatocyte suspensions. 66 48

Blood-glucose concentration is tested in male volunteers before and on the 1st, 3rd, 7th, 15th, 20th, 30th and 60th min after intravenous administration of oxytocin in doses of 0.1 IU/kg. In the first minutes after the injection there is a hypoglycaemic tendency in the changes of the blood glucose concentration, maintained in 60 per cent of the cases, while in the remaining subjects slight hyperglycaemia after the 7th min is observed. Simultaneously, hyperemia of the skin, moderate decrease in the diastolic blood pressure and tachycardia are observed. The effect of oxytocin is associated with increased influx of blood in the adipose tissue, where the glucose is metabolized with the involvement of the specific oxytocin receptors. The late hypoglycaemia is associated with oxytocin-inhibited insulin decomposition, the hyperglycaemia--with the domination of the sympathoadrenal activation in some of the subjects examined. A conclusion is reached that the effect of oxytocin on carbohydrate metabolism is physiologically unimportant.
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PMID:Effect of oxytocin on the blood glucose concentration. 72 14


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