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)

Recently, it has been reported that oxytocin (OT) produces diuresis by its interaction with OT receptors in the kidney. LLC-PK1 cells have been used as a model system for renal epithelial cells. To determine if OT stimulates receptor-mediated phosphoinositide (PI) hydrolysis in LLC-PK1 cells as it does in nonrenal cell systems, we measured the release of PI hydrolysis products in LLC-PK1 cells by OT and a selective OT agonist (AK-2-60) in the absence and presence of a selective OT antagonist (KB-5-21). In addition, we determined the effect of an increase in osmolality of the incubation medium on OT-stimulated PI hydrolysis in LLC-PK1 cells. The methods involved the incubation of LLC-PK1 cells with [3H]inositol for its incorporation into membrane PI and the measurement of the release of [3H]inositol phosphates in the presence of LiCl which prevents dephosphorylation. The osmolality of the incubation media was increased from 300 mOsmol/kg of H2O to 600, 900 and 1200 mOsmol/kg of H2O by addition of NaCl and urea. In an iso-osmotic incubation medium OT (10(-11) M) produced a greater than 100% increase in PI hydrolysis in LLC-PK1 cells. The OT agonist, AK-2-60, produced a significant increase in PI hydrolysis in LLC-PK1 cells at 10(-8) M concentration. The effects of both OT and its agonist were concentration-dependent and were blocked by the OT antagonist, KB-5-21. An increase in osmolality of the incubation media decreased OT-stimulated PI hydrolysis in LLC-PK1 and abolished completely the effect of OT at 1200 mOsmol/kg of H2O.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Stimulation of phosphoinositide hydrolysis by oxytocin in renal epithelial cells. 215 51

There are several medical methods of inducing 2nd trimester abortion, each with merits and drawbacks, difficult to compare, especially when supplemental techniques are used. Drugs used are hypertonic saline, urea, natural and synthetic prostaglandins (PGs), mannitol, formalin, ethacridine lactate (Rivanol) and others for intraamniotic route; saline, PGs, Rivanol, utus paste and other extraamniotically; and the above methods combined with oral antiprogestins, iv oxytocics, in or intravaginal PGs, or mechanical cervical dilators. Few double-blind studies exist comparing drugs. About 50,000 mid-trimester abortions are done in the US yearly, about 10% of all terminations, but these cause 2/3 of all complications and half of the deaths. Saline can be used after 15 weeks, can cause hypernatremia or coagulopathy, and takes up to 72 hours unless augmented with ocytocin and/or laminaria. Urea may have less risk of coagulopathy. Rivanol is considered safer than both in some countries, e.g., Scandinavia, Eastern Europe, Israel, India and Japan. It can be instilled transcervically. Various intrauterine PGs have been compared in several doses and routes by WHO Task Force research groups and others. Extraamniotic PGs require a lower dose, cause fewer cervical lacerations, and can be used when membranes are ruptured, in molar pregnancy, at Weeks 13-15, and in cases of fibroids. This route is somewhat less effective than intraamniotic PGs, and may require multiple doses. Intraamniotic PGs act slower but are more effective, after only 1 dose. Laminaria speed up the process, but adding oxytocin increases risk of injury. PGs may be safer than saline, especially if intramuscular route is used, because there is no danger of coagulation, cardiovascular, renal or hypernatremic complications or inadvertent injection. It is possible that some of the higher complications attributed to PGs are related to selection of patients with more severe medical conditions. PGs are more expensive, and require medication for side effects.
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PMID:Intrauterine administration of drugs for termination of pregnancy in the second trimester. 222 3

This study describes a precise and sensitive method for the bioassay of 8-arginine vasotocin (AVT). The technique is based on the observation that AVT increases the permeability to urea of the isolated toad bladder and that this effect can be measured with minute quantities of AVT by suspending bladders in humid air and applying hormone on small paper disks. The hormone diffuses from the disk to the underlying epithelium where it increases permeability to urea. The bladder is filled with Ringer's fluid containing [14C]urea and the label diffuses across the bladder wall into the disk at the serosal surface. Disks are removed at timed intervals for scintillation counting. Disks containing 0.25 pg AVT accumulated 232 +/- 8 cpm of [14C]urea in 30 min, whereas control disks without hormone at a distance of 3-4 mm on the same bladder wall accumulated only 12 +/- 2 cpm. The minimal sensitivity during the summer was 0.1 pg AVT. Average values (+/- SE) for induction of a half-maximal urea permeability response in toads from all seasons were 1.4 +/- 0.3 X 10(-10) M for AVT, 7.4 +/- 1.5 X 10(-9) M for 8-arginine vasopressin, and 2.9 +/- 0.6 X 10(-8) M for oxytocin. Plasma from a hydrated toad (255 mosm/kg H2O) showed AVT-like activity of 1.53 X 10(-11) M and from a dehydrated toad (342 mosm/kg H2O) 4.86 X 10(-11) M. Because this bioassay is specific and as sensitive as the radioimmunoassay, it may serve as a useful tool for studying the physiology of vasotocin.
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PMID:Disk method for measuring effects of neurohypophysial hormones on urea permeability of toad bladder. 307 63

The bovine oxytocin precursor was expressed in Escherichia coli as a fusion protein by cloning the hormone encoding cDNA in frame behind the replicase gene of the RNA phage MS2. By step-wise extraction with different urea concentrations, the fusion protein was enriched in the 7 M urea fraction and further purified by Sephacryl S-300 chromatography. The oxytocin precursor was cleaved off the fusion protein by cyanogen bromide treatment, chromatographed on FPLC columns and identified by Western blot analysis, using antibodies raised against neurophysin.
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PMID:Expression of the bovine hypothalamic hormone oxytocin precursor in Escherichia coli. 313 40

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

Previous studies have shown a disappearance of interstitial cells from the renal medulla of rats with hereditary diabetes insipidus (Brattleboro) when the animals were treated with vasopressin in high doses. The present study was undertaken to elucidate the mechanisms behind this cell loss. The disappearance of interstitial cells from the renal medulla of Brattleboro rats was quantitatively determined by electron microscopic stereology after various types of treatment. A considerable decrease in the volume density of interstitial cells was induced by the administration of either 8-arginine vasopressin or 1-desamino-8-D-arginine vasopressin. This lesion of the interstitial cells was not prevented by the simultaneous administration of oxytocin. Even a 48-hour period of water deprivation also resulted in a slight decrease in the volume density of interstitial cells. The results indicate that the observed loss of renal medullary interstitial cells is not a direct effect of the hormone on the cells but probably secondary to the marked increase in the renal medullary solute (urea) concentration. The fact that animals with hardly any renomedullary interstitial cells concentrated their urine to a virtually normal level shows that these cells cannot play an important role in the concentrating mechanism. The interstitial cells recovered rapidly when the vasopressin treatment was discontinued, but it could not be determined whether this was due to local proliferation or to the immigration of cells from extrarenal tissue.
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PMID:Loss of renomedullary interstitial cells in Brattleboro rats after vasopressin treatment. 335 33

In order to determine whether oxytocin release is controlled by an osmoreceptor mechanism identical with that for vasopressin release, the plasma oxytocin concentration and plasma osmolality were measured during intraatrial infusion and after intraventricular injection of various osmotic solutions in unanesthetized rats. Intraatrial infusion of 0.6 M NaCl Locke solution (L.S.) or 1.2 M mannitol L.S. elevated plasma oxytocin significantly, while 1.2 M urea L.S. caused only a small increase and isotonic L.S. did not change in plasma oxytocin. All hypertonic solutions produced significant and similar increases in the plasma osmolality. Plasma oxytocin was positively correlated with plasma osmolality in the animals infused with hypertonic NaCl or mannitol but not in the animals infused with hypertonic urea. The injection of 2 microliters of 0.6 M NaCl artificial cerebrospinal fluid (CSF) or 1.2 M mannitol CSF into the third ventricle caused a significant increase in plasma oxytocin immediately (5 min after injection) without changing plasma osmolality, while the intraventricular injection of 1.2 M urea CSF or isotonic CSF produced no significant change in plasma oxytocin. These results indicate that oxytocin release is controlled by osmoreceptors rather than Na receptors, that the adequate stimulus for the osmoreceptors is one which produces cellular dehydration and that the osmoreceptors are located in the brain region which is accessible to osmotic agents from both the outside and inside of the blood-brain barrier. Since the organum vasculosum of the lamina terminalis (OVLT) lacks a blood-brain barrier and is known to be involved in osmotic control of vasopressin release, a lesion was made in the anteroventral region of the third ventricle which encompasses the OVLT and the effect of hypertonic NaCl infusion on oxytocin release was examined. No significant increase in plasma oxytocin was observed after intraatrial infusion of 0.6 M NaCl L.S. in the lesioned rats. All of these findings lead to the conclusion that oxytocin release is under the control of osmoreceptors identical to those for vasopressin release.
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PMID:Osmoreceptor mechanism for oxytocin release in the rat. 338 52

To determine the effects of fluid restriction in induced labour with oxytocin in 5% dextrose solution, maternal venous blood and fetal cord venous blood were examined in 164 mothers in induced labour and 29 mothers with a spontaneous onset of labour. After satisfactory uterine activity was induced either the oxytocin infusion was managed according to routine delivery unit practice (n = 36), or infusion rates were halved (n = 45), or quartered (n = 43), or discontinued (n = 40). Despite fluid restriction during labour the mean sodium concentration in maternal blood or cord blood had fallen to a similar extent in all four induced groups at delivery. Potassium, urea, creatinine, total protein, and albumin in maternal blood or cord blood were affected differently by induced labour as compared with sodium. The fall in sodium concentration in maternal blood was a more consistent reflection of the total volume of fluid received, mean infusion rates and cord blood sodium after infusion rates were quartered or discontinued. The incidence of hyponatraemia was 5% in mothers and 8% in infants. A comparison of hyponatraemic and normonatraemic cord blood showed no significant differences in serum bilirubin levels or red cell counts, but more hyponatraemic infants developed neonatal jaundice. It is suggested that in induced labour fluid restriction alone does not prevent hyponatraemia and neonatal jaundice.
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PMID:Oxytocin induction of labour: hyponatraemia and neonatal jaundice. 377 Feb 80

A particular concern of gynecologists is the increased incidence of spontaneous midtrimester abortion following vaginal termination, especially in primigravid women between 10-14 weeks gestation. Intraamniotic prostaglandins (PG) have been reported to be particularly effective, but abortion is not guaranteed to occur within 24 hours after a single injection and repetition of therapy or intravenous oxytocin may be required to complete the process. A new method, intraamniotic PGE2 (10 mg) combined with urea (80 g) has been tested in a small group (n=5) of primigravid women aged 17-22 and with gestational size of 17-20 weeks. PGE2 alone was administered in another group (n=5) with similar age, parity, and gestation. The combined regimen had a significantly shorter mean time to abortion (8 hours 2 minutes) compared to the PG alone therapy (22 hours, 14 minutes) (t=2.731, p0.05). Abortion was complete in the combined regimen but was incomplete in the PG alone regimen.
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PMID:Intra-amniotic prostaglandin E 2 and urea for abortion. 412 Jul 64

1. The interaction between lipid monolayers spread on the surface of water and oxytocin, [8-arginine]-vasotocin and [1-asparagine-5-valine]-angiotensin II in the subphase was investigated in a Langmuir surface trough by studying the changes in pressure produced on injection of various quantities of the polypeptide solution under the film. 2. The effect of 2m- and 4m-urea on the character of the adsorption is reported. 3. Structures for the adsorbed films formed in this way are suggested. 4. If the lipid monolayer is taken as a suitable model of cell membranes, then it may be supposed that the effect of such structures forming in cell membranes would be to provide effective ;pores' to facilitate the movement of water and other small molecules across the membrane.
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PMID:Interaction of polypeptide hormones with lipid monolayers. 429 25


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