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 effect of oxytocin on phosphoinositide metabolism as well as on membrane protein phosphorylation in myometrial tissue was studied. Oxytocin enhanced the 32P incorporation into phospholipids in myometrial tissue. The effect of oxytocin on phosphoinositide metabolism was also detected in plasma membrane of 20 days pregnant rats. Phosphorylated membrane lipids have been analysed and phosphatidylinositol 4, 5-bisphosphate proved to be the main reaction product. Oxytocin enhanced the 32P incorporation into phospholipids measured in the first 30 sec then the labeling decreased more rapidly then in case of the control. The effect of oxytocin proved to be concentration dependent. The protein phosphorylation was also influenced by oxytocin. However the amount of alkylphosphate formed depended on the presence or absence of Ca2+, Ca2+-calmodulin and cyclic AMP, oxytocin influenced the protein phosphorylation in the presence of Ca2+-calmodulin only.
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PMID:Oxytocin regulates Ca2+ level in myometrium by influencing phosphoinositide metabolism. 255 23

1. We investigated the effect of trypsin (Tryp) on basal, stimulated and fluphenazine (FPZ)-inhibited net water flow (Jw) through isolated toad skin (Bufo arenarum). 2. Epidermal Tryp (20 min) promoted an increase in basal Jw which was dose-dependent (maximal with 0.5 mg/ml) and was prevented by a Tryp inhibitor (SBTI). 3. Tryp treatment inhibited the subsequent response to substances known to act before (oxytocin, Oxy) or after cyclic AMP (cAMP) generation (theophylline). 4. Tryp-induced Jw was not additive with the maximal response to Oxy or theophylline and did not modify FPZ's inhibitory effect on stimulated Jw. 5. Dermal Tryp (0.5 mg/ml, 20 min) did not modify basal, but inhibited Oxy and isoproterenol-stimulated Jw, without altering the response to theophylline or db-cAMP. 6. Collectively, our results show a differential action for epidermal and dermal Tryp. Tryp's side-selective action enables its use as a pharmacological tool in the functional dissection of Jw across toad skin.
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PMID:Trypsin affects basal and stimulated osmotic water permeability in isolated toad skin. 256 54

The synthesis of new radiolabelled compounds and the evolution of the techniques designed to study the hormonal receptors allow a better understanding of their properties. Three types of vasopressin receptors have been described: the V1a receptor of liver and blood vessels, the V1b receptor of hypophysis and the V2 receptor of kidney. Such a classification was based on two criteria: The structure of the binding site and the nature of the second messenger produced. The V2 receptor coupled positively to adenylate cyclase regulates the water reabsorption via the increase of intracellular cyclic AMP. The V1a and V1b receptors involved in glycogenolysis, contraction and probably neurotransmission mobilize intracellular calcium via a positive coupling to phospholipase C. These two receptors exhibit different recognition patterns for vasopressin analogues. In mammals, the oxytocin receptors are mainly involved in myometrial contraction and lactation. Their characterization are generally difficult since they also interact with vasopressin and are sometimes colocated with vasopressin receptors. As for V1 receptor, they are coupled to phospholipase C and mobilized intracellular calcium. The receptors of angiotensin II regulate the blood pressure by different mechanisms. They are coupled to at least two transduction mechanisms (positive coupling to phospholipase C and negative coupling to adenylate cyclase). Electrophysiological data seems to indicate that such receptor may also control a calcium channel. Yet different molecules (cAMP, calcium, inositol phosphates, diacyl-glycerol) trigger the hormonal effect of angiotensin II inside the cell.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Vasopressin, oxytocin and angiotensin receptors in mammals]. 269 9

To investigate the bioenergetics of uterine muscles in vivo, we examined the energy state of mouse preterm uterus by means of magnetic resonance spectroscopy. Full-term mouse uterus contained ATP, PCr, phospho-di and mono ester (PDE and PME) and inorganic phosphate (Pi). The oxytocin-induced uterine muscle contraction peaks level and positions changed. Multiple peak analysis indicated a muscle contraction induced increase in the Pi concentration and decrease in the PCr concentration. The peak position of Pi was shifted in the contractive state also, indicating that the intracellular pH was lower than in the non-contractive state and this low pH level was recovered within several minutes. There was no change in the AMP peak height in the contractive and non-contractive states. These data indicated that the energetics of mouse uterine muscle was maintained by the ATP-PCr system and acidosis of muscle was recovered within several minutes at rest. The constant AMP peak levels may indicate that phosphorylase is not regulated by AMP, but the phosphorylated phosphorylase kinase and pH levels in the contractive and non-contractive states also may indicate that phosphorylase kinase is not regulated by proteolysis or by the intracellular pH level but by the elevated intracellular calcium ion and calmodulin system.
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PMID:[The study of bioenergetics of mouse pregnant uterine muscle by magnetic resonance spectroscopy (MRS)]. 276 62

The hydroosmotic responses induced by oxytocin and 8-bromo-cyclic AMP, in frog and toad urinary bladders, were recorded minute by minute. 3HHO and 45Ca unidirectional fluxes as well as prostaglandin B2 liberation were also measured. It was observed that: (1) Addition of the calcium ionophore A23187 or quinidine to the serosal bath inhibited the response to oxytocin, but not to 8-bromo-cyclic AMP, while increasing prostaglandin E1 liberation into the serosal but not into the mucosal bath. (2) Addition of A23187 to the mucosal bath induced a transient and temperature-dependent inhibition of the response elicited by 8-bromo-cyclic AMP. The time-course of this reduction in water permeability and its sensitivity to medium temperature were similar to those observed after the withdrawal of agonist, but clearly different of those observed after intracellular acidification. (3) The hydroosmotic response was also transitorily inhibited when the Ca2+ concentration was step-changed in the mucosal bath. (4) When added to the mucosal or to the serosal baths, the ionophore increased either the apical or the laterobasal Ca2+ permeabilities. It is concluded that manipulation of intracellular Ca2+ interferes with the hydroosmotic response at two different levels. (1) A first target point located 'pre-cyclic-AMP production'. This effect would be mediated by prostaglandin liberation. (2) A second target point located after cyclic AMP production and before the 'temperature-dependent rate-limiting step'. This effect is probably related to the mechanism controlling the insertion and removal of water channels.
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PMID:Intracellular Ca2+ concentration and the antidiuretic hormone-induced increase in water permeability: effects of ionophore A23187 and quinidine. 282 86

To investigate the response of cyclic nucleotides to the oxytocic agents administered for induction of labor, plasma concentrations of cyclic AMP (cAMP) and cyclic GMP (cGMP) were determined by radioimmunoassay during spontaneous labor and labor induced by oxytocin (OT), prostaglandin F2 alpha (PGF2 alpha), or PGE2 (PGE2). Subjects were 7 Japanese women in each labor group. Plasma cAMP levels significantly rose at the time of crowning of the fetal head in all 4 groups. They did not increase until that time in the 3 labor groups (spontaneous, OT-induced, and PGF2 alpha-induced labor groups). In the PGE2-induced labor group, plasma cAMP levels were significantly higher at labor onset (mean +/- SEM = 16.5 +/- 1.3 pg/ml) when compared to the pretreatment values (13.7 +/- 1.0 pg/ml), and increased thereafter gradually toward the time of crowning of the head (26.3 +/- 2.0 pg/ml). Plasma cGMP levels in the OT-induced group significantly rose after the onset of labor and remained at a high level until expulsion of the fetus. Plasma cGMP levels in the other groups did not change significantly throughout labor. These results suggest that cAMP may be involved in the labor process induced by PGE2, and that cGMP may be in that induced by OT.
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PMID:Changes in plasma cyclic AMP and cyclic GMP during spontaneous labor and labor induced by oxytocin, prostaglandin F2 alpha and prostaglandin E2. 284 34

The effect of both lipolytic and antilipolytic hormones on the turnover of phosphatidylcholine in freshly isolated rat adipocytes was investigated. Treatment of adipocytes with agonists such as glucagon or isoprenaline that stimulate lipolysis through a cyclic AMP-dependent mechanism caused an increase in the incorporation of [Me-3H]choline into phosphatidylcholine. Pulse-chase studies indicated that the stimulation was due to an increase in the conversion of choline into phosphatidylcholine, which was both time- and dose-dependent. The stimulatory effect of isoprenaline was inhibited in a dose-dependent manner by oxytocin or insulin. Oxytocin inhibited the incorporation of [Me-3H]choline into phosphatidylcholine in both the presence and the absence of isoprenaline, whereas in the absence of isoprenaline insulin increased the incorporation of [Me-3H]choline into phosphatidylcholine. The effects of isoprenaline, oxytocin and insulin on the incorporation of [3H]choline into phosphatidylcholine were paralleled by changes in the activity of CTP:phosphocholine cytidylyltransferase.
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PMID:Hormonal regulation of phosphatidylcholine synthesis by reversible modulation of cytidylyltransferase. 284 24

1. In the intact guinea-pig myometrium, carbachol and oxytocin stimulated a specific receptor-mediated phospholipase C activation, catalysing the breakdown of PtdIns(4,5)P2 with the sequential generation of InsP3, InsP2 and InsP. Stimulation of muscarinic receptors also triggered an inhibition of cyclic AMP accumulation caused by prostacyclin. 2. NaF plus AlCl3 mimicked the effects of carbachol and oxytocin by inducing, in a dose-dependent manner, the generation of all three inositol phosphates as well as uterine contractions. AlCl3 enhanced the fluoride effect, supporting the concept that A1F4- was the active species. Under similar conditions, fluoroaluminates activated the guanine nucleotide regulatory protein Gi, reproducing the inhibitory effect of carbachol on cyclic AMP concentrations. 3. Both carbachol- and oxytocin-mediated increases in inositol phosphates, as well as contractions, were insensitive to pertussis toxin, under conditions where the expression of Gi was totally prevented. Cholera toxin, which activates Gs and enhances cyclic AMP accumulation, failed to affect basal or oxytocin-evoked inositol phosphate generation, but induced a slight, though consistent, attenuation of the muscarinic inositol phosphate response, which was similarly evoked by forskolin. 4. The data provide evidence that, in the myometrium, (a) a G protein mediates the generation of inositol phosphates and the Ca2+-dependent contractile event, (b) the relevant G protein that most probably couples muscarinic and oxytocin receptors to phospholipase C is different from Gi and Gs, the proteins that couple receptors to adenylate cyclase, and (c) cyclic AMP does not seem to control the phosphoinositide cycle, but rather exerts a negative regulation at the muscarinic-receptor level.
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PMID:Fluoroaluminates mimic muscarinic- and oxytocin-receptor-mediated generation of inositol phosphates and contraction in the intact guinea-pig myometrium. Role for a pertussis/cholera-toxin-insensitive G protein. 284 25

The effects of fluphenazine, a phenothiazine calmodulin inhibitor, on the osmotic water flow (Posm) across isolated skins of Bufo arenarum toads were tested. Fluphenazine inhibited the increase in Posm induced by agents known to act through the cyclic AMP system (oxytocin, db-cAMP, theophylline, KCl and isoproterenol). The inhibitory effect was faster and more intense when the drug was present in the epidermal bath, and persisted after rinsing the preparation for 100 min. Our results indicate that phenothiazine's action may be primarily exerted at a site distal to cyclic AMP generation.
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PMID:Inhibition of stimulated osmotic water flow by fluphenazine, a calmodulin inhibitor, in the isolated toad skin. 286 Oct 50

Captopril (CA), a specific inhibitor of kininase II, did not alter osmotic water permeability (Posm) when present in the mucosal bath of the urinary bladder isolated from the toad Bufo arenarum at a concentration of 2.3 X 10(-3) M. This treatment, however, caused a 65% enhancement in the increase in Posm following serosal exposure to vasopressin, oxytocin or theophylline, agents that increase intracellular cyclic AMP levels. The effect of captopril was prevented by procedures that reduce the kallikrein (KK)-like alkaline esterase activity present in the bladder (such as simultaneous exposure to 2.3 X 10(-5) M aprotinin, or pretreatment of the toads with 0.1 N NaCl for several days before the experiment) or by replacing the mucosal bath with fresh solution of identical composition after exposure to captopril. In contrast, changing the serosal bath did not alter the effect of the drug. These results are consistent with an effect of CA at a step beyond cAMP generation, and suggest it is mediated by release of a soluble factor, probably a kinin, into the mucosal bath. These observations, together with data previously published, suggest that the KK-kinin system may participate in the control of epithelial water and electrolyte permeability in the toad bladder. In particular, under environmental stress, it may become important in the regulation of the animal's extracellular fluid volume, thus exhibiting an adaptive value.
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PMID:A role for the kallikrein-kinin system in the regulation of osmotic water permeability in the toad bladder. 287 44


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