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

100 term (gestation at least 37 weeks), vertex presenting, vaginally delivered, and fetomaternal blood-group-compatible neonates were studied to evaluate the pathogenesis of neonatal hyperbilirubinaemia induced by oxytocin. 50 infants were born after oxytocin infusion for augmentation of labour and the other 50 were delivered spontaneously. The babies born after oxytocin induction of labour attained significantly higher serum bilirubin levels at age 72 +/- 12 hours than the controls. Infants born after oxytocin showed significant hyponatraemia, hypo-osmolality, and enhanced osmotic fragility of erythrocytes at birth. These biochemical and physiological alterations can be explained by the antidiuretic effects of oxytocin and concomitant administration of large quantities of electrolyte-free dextrose solutions used to administer it. Our observations suggest that cord serum sodium and/or osmolality should be estimated and infants with serum sodium less than 125 mmol/l and/or osmolality less than 260 mmol/kg should be considered for prophylactic administration of phenobarbitone.
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PMID:Pathogenesis of oxytocin-induced neonatal hyperbilirubinaemia. 47 17

1. The central ganglia of a number of gastropod molluscs (including the marine snail Aplysia californica and the terrestrial snail Helix pomatia) contain neurones which exhibit endogenous patterns of oscillatory activity. 2. This oscillatory activity can be modulated for long periods of time by synaptic and hormonal stimulation. 3. Stimulation of appropriate pre-synaptic nerves causes long-lasting hyperpolarization in these neurones, with complete abolition of oscillatory activity. This synaptic response is mediated by an increase in K+ conductance, together with a decrease in inward (Na+/Ca2+) conductance. The ionic conductances affected by synaptic stimulation are those responsible for producing the rhythmic oscillations. 4. The oscillatory activity can also be modulated by the vertebrate neurohyophyseal peptides, vasopressin and oxytocin, and by an endogenous peptide-containing extract of molluscan ganglia. In contrast to synaptic stimulation, these agents cause an increase in oscillatory activity. 5. The endogenous molluscan factor which produces an increase in oscillatory activity can be purified by affinity chromatography on bovine neurophysin linked to Sepharose. This indicates that the molluscan nervous system may contain a neurohypophyseal-like peptide. 6. Oscillatory activity can be modulated by manipulation of cyclic nucleotide metabolism in these neurones. Increases in cAMP alone are associated with abolition of oscillatory activity; this mimics long-lasting synaptic hyperpolarization. Increases in cAMP and cGMP together are associated with an increase in oscillatory activity and mimic the effects of the vertebrate and molluscan peptides. Thus, it is possible that cyclic nucleotides play a role in these physiological responses.
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PMID:Synaptic and hormonal modulation of a neuronal oscillator: a search for molecular mechanisms. 51 75

Intravenous injection of 20 International Units (IU) of oxytocin in the form of synthetic oxytocin or neurohypophyseal extract preparations to dehydrated cows that had already undergone twelve hours of water withdrawal did not produce antidiuresis but rather rise of diuresis accompanied by saluretic effects. Increase in diuresis occurred also in hyperhydrated cows, following water application, provided that oxytocin or vasopressin preparations had caused antidiuresis and saluresis and, consequently, changed urine composition to osmotic pressures beyond the limit values between 650 and 750 mosmol/kg. Rehydration of cow may be associated with retardation of diuresis by four hours or more. If oxytocin or vasopressin are given in the phase of such rehydration, the period between water application and the onset of water diuresis may be defined as "blocked water diuresis". Continuous infusion of 0.34 or 0.8 IU of oxytocin per minute up to 3.5 hours did not cause water intoxication in hyperhydrated cows, though blood plasma values for osmotic pressure had dropped to 244 mosmol/kg, while Na+ concentration had gone down to 116 mmol/l.
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PMID:[Studies of the induction of diuresis increase and water intoxication induced diuresis inhibition by oxytocin and vasopressin in lactating cattle]. 54 13

A study of 887 consecutively born immigrant Greek and 220 Anglo-Saxon Australian infants has shown that serum bilirubin concentrations are influenced by these factors: breast feeding, delivery with forceps, gestation, birthweight, sex of the infant, presence of hypoxia, presence of blood group incompatibility, a positive direct Coombs's test, maternal sepis, and administration to the mother of promethazine hydrochloride, reserpine, chloral hydrate, barbiturates, narcotic agents, diazepam, oxytocin, aspirin, and phenytoin sodium. Apart from the administration of promethazine hydrochloride, reserpine, chloral hydrate, and quinalbarbitone sodium, only two factors, breast feeding and delivery by forceps, occured with different frequencies in the immigrant Greek and the Australian infants. Among the Greek infants with jaundice, there were few where the cause of the jaundice was inapparent. The immigrant Greek and Australian newborn populations were therefore remarkably similar. Since differences of frequency and severity of jaundice do exist in infants born in Greece, this difference must be lost when the parents emigrate, and therefore an environmental factor must be incriminated as the causative agent for jaundice of unknown origin in Greece.
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PMID:Factors influencing jaundice in immigrant Greek infants. 62 18

The influence of oxytocin on the intracellular Na+ and K+ concentrations, the level of transmembrane potential differences, and on the relative ionic permeability (PNa/PK) of the apical zones of the superficial epithelium membrane was studied in experiments on the isolated frog gallbladder (GB). Oxytocine introduced into the outer incubation solution in a dose of 20 mulliunits/ml caused a reduction of transmembrane potential difference, and an increase of PNa/pk coefficient and an insignificant shift of the Na+ and K+ concentrations in the intracellular medium. Thirty minutes after the oxytocine action of the organ the membrane potential (MP) of the cells decreased from 52.7 mV to 38.7 mV (the cell is negatively charged inside), and PNa/PK increased from 0,083 (control) to 0,175 (test) with a simultaneous increase in the intracellular Na+ concentration by 18.3 milliequiv./kg of (H2O)i. Such a shift in the intracellular Na+ and K+ concentrations may cause a decrease of the MP by only--0.7 mV, but actually the membrane potential decreased by--14.0 mV. Thus, the reduction of the transmembrane potential difference results from increase of PNa/PK under the influence of oxytocine. No electrogenic ionic transport through the apical membrane of frog gallbladder epithelial cells was revealed.
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PMID:[Effect of oxytocin on the electrical potential and ion permeability of the apical membrane of frog gall bladder epithelial cells]. 63 80

The haemodynamic effects of oxytocin (Syntocinon) and methyl ergometrin (Methergin) were studied in 9 healthy females in the first trimester of pregnancy. The patients were anaesthetized with sodium thiomebumal, pethidine and pancuronium bromide and ventilated on a Manley respirator. 10 i.u. oxytocin given as an i.v. bolus brought about a fall in femoral arterial pressure of 40%, systemic resistance 59% and pulmonary resistance 44% 30 sec after injection. However, the heart rate increased 31% and stroke volume 17%, so that the cardiac output increased by 54%. The pulmonary arterial pressure and wedge pressure were increased by 33% and 35%, respectively 150 sec after injection. No changes were seen in the haemodynamic parameters during infusion of 80 mU oxytocin for 10 min. 0.2 mg Methergin brought about an increase in the femoral arterial pressure of 11%, pulmonary arterial pressure 27% and wedge pressure 31%, with no changes in the other measured parameters. The use of oxytocic drugs in patients with compromised circulation is discussed.
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PMID:Haemodynamic effects of oxytocin (syntocinon) and methyl ergometrine (methergin) on the systemic and pulmonary circulations of pregnant anaesthetized women. 63 63

Release of oxytocin from the rat posterior pituitary lobe incubated in situ and from the hypothalamic end of the cut pituitary stalk. Acta Physiol. Pol., 1978, 29 (2):97--105. Using the method of incubation in situ of the posterior pituitary lobe and washing the hypothalamic end of the divided pituitary stalk the activity of neurosecretory neurons was investigated directly. The oxytocic activity of the fluid incubating in situ the posterior pituitary lobe or washing the hypothalamic end of the cut pituitary stalk was determined on the rat myometrium. The oxytocic activity disappeared from this fluid after inactivation with sodium thioglycolate. The samples of the fluid incubating the posterior pituitary lobe obtained at 30 min intervals showed alternatingly increased or decreased oxytocic activity. In the fluid washing the cut pituitary stalk the activity was highest from 31 to 60 minutes after division of the stalk.
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PMID:Release of oxytocin from the rat posterior pituitary lobe incubated in situ and from the hypothalamic end of the cut pituitary stalk. 65 29

(8-Arginine)vasopressin, (8-arginine)vasotocin, oxytocin and oxypressin, the 'ring' derivatives pressinamide and tocinamide, and the extended-chain analogues Pro-Arg-Val-(8-arginine)vasopressin and (8-arginine)vasopressinoyl-Ala-Met-Ala-NH(2), were synthesized by the solid-phase method and purified by sequential gel filtration on Sephadex G-15 in 50% acetic acid and 0.2M-acetic acid. Controlled oxidation of the thiol groups of the reduced peptides obtained after deprotection with sodium in liquid ammonia gave rise to products that depended on the length of the peptide chain: (i) nonapeptides gave monomer and dimer species, (ii) hexapeptides produced mixtures containing higher polymers, and (iii) dodecapeptides gave predominantly monomer with some dimerized material. The evidence suggests that the presence of the acyclic tail tripeptide in the nonapeptide hormones induces a conformation in the preceding hexapeptide that favours the formation of an intramolecular disulphide bond. For (8-arginine)vasopressin, intramolecular disulphide-bond formation is enhanced by extension of the peptide chain from either the N- or the C-terminus. The possible significance of these studies to neurohypophysial hormone-prohormone relationships is discussed.
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PMID:Influence of the peptide-chain length on disulphide-bond formation in neurohypophysial hormones and analogues. 69 27

Using appropriate amino acid active esters (3 eq.) in presence of HOBt (1 eq.) and employing DPM protection for the thiol function of cysteine, a rapid synthesis of oxytocin in the solid phase has been accomplished. The DPM group has been removed by sodium-liquid ammonia reduction since boiling TFA is ineffective. Desaminooxytocin and 4-Thr-oxytocin have been synthesized using lesser quantities of amino acid active esters (1.5 eq.) in presence of HOBt (1 eq.), but the durations of coupling are longer. The solid-phase synthesis of desamino-oxytocin using appropriate Boc-amino acids in presence of DCCI in toluene medium has been described. Toluene does not exert any significant accelerating influence on the coupling rate as it does when active esters are employed.
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PMID:Solid-phase synthesis of oxytocin, desaminooxytocin and 4-Thr-oxytocin using active esters in presence of 1-hydroxybenzotriazole. 70 Sep 21

Sensitive and highly specific RIAs for arginine vasopressin (AVP) and oxytocin (OT) were utilized to assess the specificity of neurohypophyseal hormone release after hemorrhage or infusion of hypertonic saline to trained conscious dogs. Phlebotomy of 12.5 and 25 ml/kg produced increases in plasma AVP from 1.0 +/- 0.2 to 7.8 +/- 2.1 and 41.6 +/- 9.7 (SEM) microunit/ml respectively, and both responses differed significantly from values in control experiments (P less than 0.01 after the first phlebotomy and P less than 0.001 after the second phlebotomy). Plasma OT concentrations rose from baseline values of 1.1 +/- 0.4 to 3.3 +/- 0.6 and 8.3 +/- 1.7 microunit/ml (P less than 0.005 and P less than 0.001 compared to controls); plasma osmolality and sodium concentrations were unchanged. Both log AVP and log OT were highly correlated with the quantity of blood removed (r = 0.92 and -0.82, each P less than 0.001). Infusion of hypertonic (20g/dl) NaCl (3.4 meq/kg) over 20 min caused plasma osmolality and sodium to rise from 304 +/- 1.0 mosm/kg and 143 +/- 3.0 meq/liter to 316 +/- 1.0 mosm/kg and 150 +/- 3.0 meq/liter (each P less than 0.001). Plasma AVP rose from 1.5 +/- 0.2 to 2.4 +/- 0.2 microunit/ml (P less than 0.0025) and OT rose from 1.2 +/- 0.5 to 2.6 +/- 0.7 microunit/ml (P less than 0.005). The stimulus response ratios (change in log hormone concentration divided by the rise in plasma osmolality) were comparable for both hormones (0.024 +/- 0.006 for AVP and 0.031 +/- 0.008 for OT; P less than 0.4). The data indicate that hemorrhage or hypertonic saline stimulate release of both AVP and OT. After hemorrhage, there is greater stimulation of AVP than OT, whereas there is comparable stimulation of both peptides after hypertonic saline.
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PMID:The effect of hemorrhage and hypertonic saline upon plasma oxytocin and arginine vasopressin in conscious dogs. 74 39


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