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)

The basal rate of water reabsorption and its acceleration by oxytocin, cyclic AMP (cAMP) or serosal hypertonicity in frog urinary bladders were monitored before and after exposure of the mucosal surface to sulfhydryl (SH) reactive reagents. The following observations were made: 1. N-ethylmaleimide (NEM, 10(-5)M) did not modify the basal water flux, but did potentiate the hydrosmotic response to oxytocin. At higher NEM concentrations, an increase in the basal flux was observed, while the oxytocin-induced water flux was strongly inhibited, if not, nullified. 2. Iodoacetamide (IAM, 10(-3)M) did not modify the basal water flux but did inhibit the oxytocin-, cAMP-, and serosal hypertonicity-induced increase in water permeability. Furthermore, the time course of the hydrosmotic response to oxytocin was significantly increased. 3. 5,5' dithio-bis-(2-nitrobenzoic acid) (DTNB, 10(-3)M) modified neither the basal nor the oxytocin-induced water flux when incubated at pH 8.1, but potentiated the inhibitory effect of NEM. However, at a mucosal pH of 6.5, DTNB inhibited the response to oxytocin by 30%. These results suggest that: (1) the three SH reagents affect differently the basal and the oxytocin-induced water pathways; and that (2) each of the changes in the oxytocin-induced paths occurs at a step following the hormonally-induced increase in intracellular cAMP concentration.
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PMID:Effect of SH-group reagents on net water transport in frog urinary bladder. 350 31

The effects of prostacyclin (PGI2) on the uterine muscle of pregnant rats were studied in terms of uterine contraction and the variation in cyclic nucleotides. The following results were obtained: The administration of PGI2 stimulated the pregnant uterine muscle (in vitro). The oxytocic potency of PGE1-analog (ONO-802) was greatest, followed in order by that of PGF2 alpha and PGI2. The effect of 5-lypoxygenase inhibitor (AA-861) on uterine contraction was greatest under the administration of LTC4, followed in order by PGI2, oxytocin, PGF2 alpha, LTD4 and ONO-802. The effect of AA-861 was greater under the simultaneous administration of LTD4/LTC4 and ONO-802 than under the simultaneous administration of oxytocin and ONO-802. Terbutaline exerted the inhibitory effect on each of the oxytocies within two minutes in all cases. Its inhibitory effect on the oxytocics was slight in the cases to which oxytocin or ONO-802 was administered. Changes in cyclic nucleotides in the bath medium were determined before and after the administration of each drug. When PGI2 was administered, both c-AMP and c-GMP increased and showed a pattern which was different from that for other oxytocics. This tendency was also observed when PGI2 and other drugs (terbutaline, ONO-802 and AA-861) were administered together.
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PMID:[A basic study of the oxytocic effect of prostacyclin on the uterine muscle in pregnant rats]. 353 66

The isolated urinary bladder of the toad responds to neurohypophyseal hormone with a net increase of water transport from the mucosal to the serosal solution in the presence of an osmotic gradient. This response is mediated intracellularly by cyclic 3',5'-adenosine monophosphate (AMP). The present study demonstrates that hydroosmotically active substances such as oxytocin, dibutyryl cyclic 3',5'-AMP, and theophylline, but not hydroosmotically inactive substances, induce the uptake of horseradish peroxidase from the mucosal solution. Peroxidase taken up by the mucosal cells is demonstrable in small tubules and vesicles, and eventually accumulates in lysosomes. The uptake of peroxidase from the serosal solution into similar bodies in the mucosal cells is not hormone-dependent. It is also shown that peroxidase does not penetrate the tight junction from either the mucosal or serosal solution. These results extend previous findings which implicated the apical membrane of the mucosal epithelium as the site affected by neurohypophyseal hormones. A mechanism based on secretory phenomena is proposed as a framework for future investigations of apical membrane permeability changes and pinocytosis.
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PMID:Correlation between pinocytosis and hydroosmosis induced by neurohypophyseal hormones and mediated by adenosine 3',5'-cyclic monophosphate. 432 55

The frog urinary bladder undergoes, in some conditions, a marked increase of its water permeability when incubated in hypertonic media. This increase was observed with various nonpermeant solutes. It seems to result from the shrinkage of an osmo-sensitive compartment of the tissue, probably the epithelial cells. Many similarities were found between this effect and the physiological increase in water permeability (hydrosmotic response) elicited by antidiuretic hormone (ADH): both were dependent on the physiological state of the animals, and although the response was slower after hyperosmolar than after hormonal challenge, the patterns of response were similar, and in both cases markedly dependent on bathing solution temperature. Norepinephrine and prostaglandin E(1), which in this tissue reduce the hydrosmotic action of ADH, presumably by inhibiting the adenyl cylase also reduced the effect of hyperosmolarity. Conversely this effect was potentiated by incubation in the presence of oxytocin, exogenous cyclic AMP, and theophylline, conditions in which the intracellular concentration of cyclic AMP is increased. These data demonstrate that the response to hyperosmolarity is elicited, at least partly, by mechanisms also involved in the physiological hydrosmotic response to ADH.
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PMID:The effect of hypertonic media on water permeability of frog urinary bladder. Inhibition by catecholamines and prostaglandin E 1 . 434 37

This is a review from the literature dealing with the physiology of prostaglandins (PGs). PGs E and F are biosynthesized from straight chain C-20 fatty acids, arachidonic acid being the precursor of 2 of the series and dihomo-linolenic acid the precursor of the other series. Availability of certain cofactors during synthesis probably determines which PG is formed. The amounts of PGs in the tissues are very low, indicating that they are biosynthesized immediately before hormone-stimulated release. PGs seem to be metabolized by all body tissues. PGE and PGF cannot act as circulating hormones since they are 95-99% deactivated by 1 passage of the blood through the lungs. The following roles of PGs in the reproductive process are discussed: 1) present in semen, they may aid in fertilization; 2) they may function as mediators between luteinizing hormone and cyclic AMP during ovulation; 3) they may facilitate release of anterior pituitary hormones; 4) they act to stimulate progesterone secretion; 5) they act in some species as the uterine luteolytic hormone; and 6) they sensitize the uterus to oxytocin during delivery. Since every body tissue appears to be able to synthesize PGs, they also have other physiological functions.
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PMID:The physiology of prostaglandins. 435 87

Studies were made to determine the effect of various contraction-inhibitors against spontaneous uterine contraction in rats during late pregnancy. 1) The duration and rate of inhibitory activity differed from inhibitor to inhibitor, showing dose-response relationship. As a result of this investigation of the changes in the intensity and frequency for 17 inhibitors, Ca-blocker, beta 2-stimulants and dibutyryl c-AMP had the strongest effects, PG-antagonist, and the anti-inflammatory drugs such as aminophylline were much weaker in their inhibitory activity. 2) When the progress of uterine inhibition was investigated on the basis of quantitative changes of PG and c-AMP in bath medium, it was found that both PGE1 and PGF2 alpha were significantly reduced after administration of terbutaline and indomethacin, c-AMP decreased significantly after administration of PGE1 analogue, oxytocin and PGF2 alpha. The c-AMP levels increased significantly after administration of terbutaline and verapamil. These were no significant changes in c-AMP levels when indomethacin and aminophylline were used. During the administration of the uterine inhibitors, c-AMP increased significantly both in vivo and in vitro. Therefore, c-AMP may be regarded as an important parameter indicating the degree of inhibition of contraction.
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PMID:The comparative actions of uterine inhibiting drugs in the pregnant rat. 611 60

An accumulation of 3H-labelled inositol phosphates is observed when prelabelled rat superior cervical sympathetic ganglia are exposed to [8-arginine]vasopressin or to muscarinic cholinergic stimuli. The response to vasopressin is much greater than the response to cholinergic stimuli. The response to vasopressin is blocked by a V1-vasopressin antagonist, and oxytocin is a much less potent agonist than vasopressin. Vasopressin causes no increase in the cyclic AMP content of ganglia. These ganglia therefore appear to have functional V1-vasopressin receptors that are capable of activating inositol lipid breakdown, but no V2-receptors coupled to adenylate cyclase. The first [3H]inositol-labelled products to accumulate in stimulated ganglia are inositol trisphosphate and inositol bisphosphate, suggesting that the initiating reaction in stimulated inositol lipid metabolism is a phosphodiesterase-catalysed hydrolysis of phosphatidylinositol 4,5-bisphosphate (and possibly also phosphatidylinositol 4-phosphate). This response to exogenous vasopressin occurs in ganglia incubated in media of reduced Ca2+ concentration. The physiological functions of the V1-vasopressin receptors of these ganglia remain unknown.
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PMID:Rapid accumulation of inositol phosphates in isolated rat superior cervical sympathetic ganglia exposed to V1-vasopressin and muscarinic cholinergic stimuli. 614 75

Adenosine 3':5' monophosphate3 (cAMP) and guanosine 3':5' monophosphate (cGMP) are known to participate in the regulation of proliferation and differentiation, the processes intimately associated with maturation of the neonate. We have therefore examined their content in the physiological nutrient of the mammalian neonate, the mother's milk. Widely fluctuating concentrations between 0.1 and 0.7, and between 0.01 and 0.15 nmol/ml, were found for cyclic AMP and cyclic GMP, respectively. Concentrations in human breast milk changed during the 5-to 15-min period of one nursing, during any 24-h period, and also during the total lactation period. Levels of cyclic GMP were generally less fluctuating and were lower during afternoon and evening; they were relatively high at the start of lactation and levelled off during the postpartum period. The ratio of the two cyclic nucleotides also fluctuated widely and was significantly different from the ratio determined on blood plasma collected at the same time. Oxytocin injection had no effect on cyclic AMP content of rat milk. The stomach content of the nucleotide in rat pups remained high for at least 1 h after suckling indicating that cyclic nucleotides remain available for intestinal absorption; whether they have any physiological function in the neonate will have to emerge from further studies.
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PMID:Cyclic nucleotides in breast milk. 625 24

The binding of vasopressin to human circulating blood cells was examined. Direct binding studies with preparations of single cell types indicated that the mononuclear phagocyte system is almost entirely responsible for binding of the hormone. Binding of 125I-8-L-arginine vasopressin (AVP) (40 pM) in the presence of excess unlabeled hormone was saturable (2.8 +/- 0.4 fmol/2 x 10(6) cells per ml), was linear with cell number, was dependent upon the concentration of the radioligand used, and was reversible. Binding equilibrium was achieved in 30--40 min at 22 degrees C. Scatchard analysis of binding at this time showed an apparent dissociation constant of 25 +/- 0.21 pM, providing an estimate of 640 +/- 80 sites/cell. Pretreatment of the cells with cytochalasin B, an agent that can block phagocytosis, did not modify radioligand binding, which indicates that 125I-AVP uptake by the cells is due to binding and not to endocytosis. Specificity of vasopressin-sensitive sites on mononuclear phagocytes was demonstrated with a series of vasopressin analogues with various degrees of antidiuretic potency, and with peptide hormones that bind to specific receptors on circulating blood cells but that lack antidiuretic activity. AVP (40 pM) elevated the intracellular level of cyclic AMP from 137 +/- 8.6 to 350 +/- 20.5 pmol/mg cell protein. The binding affinities of the various analogues were correlated with their ability to stimulate intracellular cyclic AMP synthesis (Lys8-vasopressin less than deamino(8-D-Arg)-vasopressin less than oxytocin).
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PMID:125I-8-L-arginine vasopressin binding to human mononuclear phagocytes. 626 2

When rat myometrium that had been depleted of Ca by incubation with 3 mM EGTA for 50 min was challenged with 10(-2) unit/ml oxytocin, it showed sustained contraction in a medium with no added Ca (Ca-free contraction). It also showed Ca-free contraction of similar magnitude in the presence of 1 mM EGTA. The effects on this contraction of divalent cations (Co2+, Ni2+ and Mn2+) singly and in combination with D-600 (3 X 10(-6) M) were investigated. Co2+ and Ni2+ potentiated Ca-free contraction concentration-dependently, and their effects were greater in the presence of D-600. In contrast, Mn2+ evoked a triphasic response; first transient potentiation, second relaxation, and third persistent increase in tension. D-600 did not block the first or second, but blocked the third, resulting in persistence of the second phase of relaxation. The relaxing action of papaverine on Ca-free contraction was not affected by D-600. Isoproterenol and dibutyryl cyclic AMP also relaxed the contraction.
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PMID:Oxytocin-induced Ca-free contraction of rat uterine smooth muscle: effects of divalent cations and drugs. 626 5


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