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)

Acid-base status of umbilical artery and vein blood was measured immediately after delivery in 300 cases. A slight acidosis of mixed respiratory/metabolic type was found in newborns delivered following a second stage of 10-30 min duration. After a second stage of more than 30 min the metabolic contribution to the acidosis was predominating. With Apgar scores lower than 10 the pH was found to decrease and carbon dioxide tension to increase. Induction or augmentation of labor by oxytocin did not influence the acid-base status of umbilical cord blood. Delivery by vacuum extraction or low forceps resulted in lower pH and higher carbon dioxide tension in umbilical cord blood, but the changes were associated with the indication for instrumental delivery and not with mode of delivery. A large arterio-venous difference between the acid-base parameters was usually connected to vigorous newborns and a small difference to depressed infants. The carbon dioxide tension was usually increased in newborns with decreased pH, and a close correlation between these parameter was found. No case of acidosis (pH below 7.15) was found in this population at carbon dioxide tensions below 7.2 kPa; at higher Pco2 values only 25% of the newborns were acidotic. A Pco2 level of 7.7 kPa might be used at transcutaneous carbon dioxide monitoring during labor, although the sensitivity and specificity of this parameter will have to be decided in a prospective study.
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PMID:Acid-base evaluation of umbilical cord blood: relation to delivery mode and Apgar scores. 310 7

Vasopressin and oxytocin exert pronounced effects on behaviour by a direct action on the brain. A single injection of vasopressin results in a long-term inhibition of extinction of a conditioned avoidance response suggesting that vasopressin triggers a long-term effect on the maintenance of a learned response, probably by facilitation of memory processes. In addition vasopressin improves passive avoidance behaviour, delays extinction of appetitive discrimination tasks, affects approach behaviour to an imprinting stimulus in ducklings, improves copulation rewarded behaviour of male rats in a T-maze, prevents or reverses amnesia induced by electroconvulsive shock, CO2 inhalation, pentylenetetrazol or puromycin. The majority of these effects of vasopressin in the various and sometimes relatively complex tasks may be explained by stimulatory influences of this neuropeptide on memory processes. Generally oxytocin exerts effects which are opposite to those of vasopressin and it has been suggested that oxytocin may be an amnesic neuropeptide. Various limbic system structures seem to act as the anatomical substrate for the behavioural effects of vasopressin. In particular the amygdala, the dentate gyrus of the hippocampal complex, the ventral hippocampus and the dorsal septum seem to be involved. Evidence has been obtained from experiments with homozygous diabetes insipidus rats and from experiments in which antisera were applied that endogenous vasopressin and oxytocin play a physiological role in brain processes related to memory. It appears that highly active fragments can be generated from vasopressin and experiments in which a fragment of vasopressin ([pGlu4, Cyt6]AVP-(4-8)) as well as an AVP-antagonist were used, reveal that the vasopressin receptors mediating the behavioural effects are situated in the brain and differ in specificity from the peripheral (blood pressure) vasopressin receptors. Generally the clinical data obtained so far with vasopressin treatment are in agreement with the results from animal experiments and they support the notion on the involvement of vasopressin in memory function. The sometimes reported conflicting results on vasopressin effects in certain patients (Korsakoff or Alzheimer) may have to do with the wide-spread pathology in these diseases.
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PMID:Vasopressin and oxytocin. Their presence in the central nervous system and their functional significance in brain processes related to behaviour and memory. 346 10

The nature of the activity of vasopressin which is responsible for the inhibition of renin secretion was studied by comparing the effects of vasopressin (AVP) and analogs of AVP in anesthetized water-loaded dogs. Infusion of AVP (1.0 ng/kg/min) increased mean arterial pressure (MAP) and decreased heart rate (HR) and free water clearance (CH2O). Plasma renin activity (PRA) decreased from 11.9 +/- 4.7 to 3.8 +/- 1.7 ng/ml/3 hr (p less than 0.05). A selective antidiuretic agonist, 1-deamino-8-D-arginine vasopressin (1.0 ng/kg/min), which had no effect on MAP or HR but was effective as AVP in decreasing CH2O, decreased PRA from 13.5 +/- 4.6 to 7.0 +/- 2.9 ng/ml/3 hr (p less than 0.05). Infusion of a selective vasoconstrictor agonist, 2-phenylalanine-8-ornithine oxytocin (1.0 ng/kg/min), increased MAP and decreased HR but did not decrease CH2O or PRA. A vasoconstrictor antagonist, d(CH2)5Tyr(Me)AVP (10 micrograms/kg), completely blocked the MAP and HR responses to AVP but did not block the decrease in CH2O or PRA (5.9 +/- 1.8 to 2.9 +/- 1.6 ng/ml/3 hr) (p less than 0.001). Infusion of the 0.45% saline vehicle had no significant effect on MAP, HR, CH2O or PRA. These results indicate that the inhibition of renin secretion by vasopressin in anesthetized water-loaded dogs is due to its antidiuretic activity.
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PMID:Role of antidiuretic activity in the inhibition of renin secretion by vasopressin in anesthetized dogs. 352 May 11

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

A modification of the rat isolated seminal vesicle preparation is described, emphasizing the necessity to use younger animals (40-50 days old and weighing between 125 and 150 g) and to expel thoroughly all vesicular contents. Under the experimental conditions used (tissues suspended under a resting tension of 350 mg in a continuous flow of a modified Krebs solution run at the rate of 15 ml/min, maintained at 32 degrees C, and bubbled with 5% CO2 in O2), the preparation was quite sensitive, but only to a few selected agonists, and remained viable for over 4-6 hr. Adrenaline, noradrenaline, dopamine, and acetylcholine all produced concentration-dependent and reproducible contractions. However, histaminergic, serotoninergic, purinergic, and opioid agonists were inactive as were prostaglandins of the E and F series and the polypeptides angiotensin, vasopressin, and oxytocin. In general, the tissue was rather insensitive to relaxant drugs, with only papaverine and sodium nitrite producing some relaxation in tissues previously contracted by carbachol. Advantages of the preparation include marked responsiveness, but only to a few selected agonists, and suitability for use as a paired tissue. It is suggested that employed under suitable experimental conditions, the preparation deserves a more frequent consideration for use during pharmacological investigations concerned with postsynaptic aspects of noradrenergic or cholinergic transmission.
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PMID:Pharmacological evaluation of the isolated rat seminal vesicle preparation. 395 Dec 38

Vasopressin and oxytocin exert pronounced effects on behavior by a direct action on the brain. A single injection of vasopressin results in a long-term inhibition of extinction of a conditioned avoidance response suggesting that vasopressin triggers a long-term effect on the maintenance of a learned response, probably by facilitation of memory processes. In addition vasopressin improves passive avoidance behavior, facilitates retention of sexually motivated T-maze choice behavior in male rats, delays extinction of an appetitive discrimination task, affects approach behavior to an imprinting stimulus in ducklings, delays the postcastration decline in copulatory behavior in male rats, prevents or reverses amnesia induced by electroconvulsive shock, CO2 inhalation, pentylenetetrazol or puromycin. The majority of these effects may be explained by stimulatory influences of vasopressin on memory processes. Generally oxytocin exerts effects which are opposite to those of vasopressin and it has been suggested that oxytocin may be an amnesic neuropeptide. Evidence has been obtained that endogenous vasopressin and oxytocin play a physiological role in brain processes related to memory. Various limbic system structures seem to act as the anatomical substrate for the behavioral effects of vasopressin and different neurotransmitter systems seem to be involved. It is postulated that in case vasopressin affects retrieval processes the site of action is located in the amygdala and the dentate gyrus of the hippocampal complex with dopamine and serotonin as the respective neurotransmitter systems involved.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Hypothalamic neuropeptides and memory. 399 53

Storage of plasma at -30 degrees C, with no prior treatment, resulted in significant (P less than 0.01) reductions in the biological and immunological activities of oxytocin after 10 days and further reductions after 20 days. Acidification with 0.1 N hydrochloric acid, or snap-freezing in solid carbon dioxide-acetone, before storage afforded some protection against these losses and a combination of both treatments preserved the biological and immunological activities for 20 days despite thawing and refreezing after 10 days.
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PMID:Loss of biological and immunological activity of oxytocin from goat plasma on storage. 407 Jul 96

A 1968 Indian study compared the effect of Norlutin (17-alpha ethynl 19-nor testosterone) and Provera (6-methyl acetoxyprogesterone) suspensions on the uterine motility of virgin rats and mice to the action of natural progesterone and testosterone. The test animals were spayed and 2 weeks later, the rats were injected with 2 mcg of estradiol benzoate daily for 3 consecutive days. The mice received .2 mcg injections. On day 4 the animals were sacrificed and the uterine horns were suspended in a 40 ml organ bath containing Tyrode solution at 32 degrees centigrade and aerated with 5% carbon dioxide in oxygen. Rat uterine movement was recorded isotonically with a linear frontal writing lever while a heart lever was used for mice. The action of the compounds was also tested on oxytocin-induced spasms. Norlutin suspension (1.25-50 mcg/ml) inhibited both amplitude and tone of uterine contraction within 2-10 minutes and lasted more than 1 hour. The uterus failed to respond to oxytocin during peak Norlutin action. A progesterone concentration of 1.25 mcg also produced uterine relaxation but its effect on contractual tone was insignificant. Graded concentrations of Provera and testosterone suspension failed to effect uterine motility in rats and mice.
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PMID:Effect of some synthetic progestational steroids on uterine contractions. 578 55

Mucosal acidification (from pH 8.1 to 6.0) reversibly inhibited the hydroosmotic responses to oxytocin, cyclic AMP and 8-bromo-cyclic AMP in frog urinary bladder. These inhibitory effects were only observed in the presence of a permeant buffer in the apical medium and could also be elicited by CO2 bubbling, even when the mucosal pH was clamped at 8.1. Acid pH reduced the oxytocin-induced net water flux faster than norepinephrine or oxytocin removal and the difference was especially important at low temperature. The time course of recovery from acid pH inhibition was, at 20 degree C, similar to that of the hormonal action, but when the medium temperature was reduced to 6-7 degrees C, the recovery from acid pH inhibition paradoxically became faster while the oxytocin action was markedly slowed down (t 1/2 of changes in net water fluxes (expressed in min): oxytocin addition at 20 degrees C, 6.2 +/- 0.9; at 6 degrees C, 24 +/- 3; oxytocin removal at 20 degrees C, 4.7 +/- 0.8; at 6 degrees C, 22 +/- 3; pH inhibition at 20 degrees C, 2.6 +/- 0.2, at 6 degrees C 2.5 +/- 0.2; recovery from pH 6 at 20 degrees C 6.5 +/- 0.9; at 6 degrees C, 2.7 +/- 0.3). These results can be explained by accepting two main loci sensitive to medium acidification: (1) the cyclase system and (2) an intracellular, temperature-independent, post-cyclic AMP site. The fact that the intramembranous particle aggregates associated with the oxytocin-induced water permeability increase did not disappear after the flow inhibition by acid pH at low temperature suggests that the second effect could be located at the water channel itself.
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PMID:Cellular pH and water permeability control in frog urinary bladder. A possible action on the water pathway. 627 53

Urinary bladders of frogs were exposed to a transepithelial proton and osmotic gradient (serosal pH 8.1, Tris or bicarbonate buffer; mucosal pH 5.8, unbuffered) while the alkalinization rate of the mucosal bath and the net water movement were simultaneously monitored. It was observed that 1) the mucosal alkalinization rate was dependent on serosal pH and buffer; 2) oxytocin increased the mucosal alkalinization rate only when serosal bicarbonate was employed, whereas the net water movement augmented both when serosal bicarbonate or Tris buffers were used; 3) amiloride did not modify the mucosal alkalinization rate either before or after oxytocin; 4) the increases in the mucosal alkalinization rate and in the net water movement induced by oxytocin (serosal bicarbonate) were negatively correlated. In other experiments intracellular pH (pHi) was estimated with the DMO distribution technique with the following results. 1) Oxytocin increased the pHi when either serosal bicarbonate or Tris buffers was used and even in the presence of a low mucosal pH (Tris buffer, pH 5.8). 2) Important cellular acidification was observed when CO2 was bubbled (to pH 5.8), whereas the hydrosmotic response to 8-bromo-cAMP was clearly inhibited. These results indicate that cellular alkalinization could play a pivotal role in action of ADH, show that ADH can modify the transepithelial pH equilibrium mechanism, and suggest that intracellular pH regulation and water permeability control can be linked regulatory processes.
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PMID:Intracellular pH, transepithelial pH gradients, and ADH-induced water channels. 630 8


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