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)

Aminophylline (250 mg., over five minutes) was infused intravenously to 10 patients with oxytocin-induced contractions. The uterine activity decreased to 87 per cent because of the effect on contraction intensity; contraction frequency was unaffected. The maximum maternal pulse rate increased to 33 beats per minute. Blood pressure was unaffected. The fetal heart rate and beat-to-beat variability increased. An increased dosage of aminophylline produced unacceptably high maternal tachycardia. Comparing the results to those produced by the beta-sympathomimetic drugs in the same experimental model, it is concluded that aminophylline exhibits poor uterine selectivity with an unfavorable cardiovascular/tocolytic ratio.
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PMID:Uterine and cardiovascular effects of aminophylline. 68 63

Arginine (AVP) and lysine vasopressin induce a weak but statistically significant increase in the water permeability of Amoeba proteus plasmalemma. Vasotocin and deaminovasopressin, which share the hydroosmotic properties of AVP on classical vertebrate systems, are without effects on Amoeba while SKF 101926, a synthetic AVP antagonist, is even more effective than the parent compound. Theophyllin and dibutyryl-cAMP do not affect AVP action on Amoeba. Lithium, oxytocin, and carbachol are also without effect. Thus, it is unlikely that either V2 (cAMP) or V1 (phosphatidylinositol choline) receptors are involved. A clear correlation has been found between the amphiphilic character of tested peptides and their effect on Amoeba water permeability. Classical amphiphilic peptides, melittin, mastoparan, and fragment 1-8 of alpha-neoendorphin, also increased water permeability in Amoeba. It is known that vasopressin can interact with artificial lipid membranes, increasing their permeability to water. We propose that amphiphilic members of the AVP family interact directly with the lipid phase of the Amoeba membrane. Their incorporation within the lipid bilayer may cause local disruptions or may create micellar water channels as shown for other amphiphilic proteins. Our observations provide a model for the early evolution of peptide hormone systems, preceding the appearance of specific membrane receptors and associated second messenger amplifying mechanisms.
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PMID:The amphiphilic action of vasopressin and analogues on the plasma membrane of Amoeba proteus. 214 31

To characterize the effects of aminophylline and nifedipine on pregnant human myometrium, in vitro contractility studies were performed on myometrial strips obtained at cesarean section. The strips were stimulated with oxytocin (800 mU/L) to simulate labor and then were exposed to increasing concentrations of aminophylline (40, 100, and 400 mumol/L) or nifedipine (5, 10, and 20 micrograms/L). Both drugs produced a dose-related decrease in contraction strength, as measured by the time-integrated force of contraction. Aminophylline lengthened the period of contraction in a manner that was not dose dependent. Low-dose nifedipine (5 micrograms/L) increased the period of contraction, but higher doses had no effect on frequency. Both drugs produced a net reduction in the effectiveness of labor, as measured by the average force (time-integrated force divided by period). These results indicate that both aminophylline and nifedipine may be clinically useful tocolytic agents.
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PMID:The effects of aminophylline and nifedipine on contractility of isolated pregnant human myometrium. 360 50

A possible role for adenylcyclase in insulin secretion was investigated. Isoproterenol, a predominantly beta-adrenergic agent, when mixed with an alpha-adrenergic blocking agent (phenoxybenzamine), stimulated insulin secretion from pieces of the rat's pancreas in vitro. Theophylline, caffeine, 3'5'-cyclic AMP, glucagon, adrenocorticotropin (ACTH), and thyrotropin (TSH), all of which are thought to act through the adenylcyclase systems in the liver and adipose tissue, also stimulated insulin secretion in vitro; oxytocin and vasopressin, which do not stimulate lipolysis in adipose tissue, were inactive. In all cases, stimulation of insulin secretion could not be detected when glucose was absent or present in only low concentrations (less than 100 mg/100 ml) and was maximal at high levels of glucose (300 mg/100 ml). When pancreatic tissue was obtained from normoglycemic rats and contained no detectable glycogen in the Islets, the stimulant effects of glucose and of theophylline were reduced or abolished by mannoheptulose and 2-deoxyglucose. When tissue was derived from rats infused for 8-10 hr with glucose and contained glycogen, theophylline, even in the absence of glucose, stimulated secretion and this effect was reduced by 2-deoxyglucose but not by mannoheptulose. It is suggested that the beta-cell contains an adenylcyclase system through which phosphorylase and possibly phosphofructokinase could be activated; and that insulin secretion could depend upon and be regulated by hormones and other substances which influence the rate at which glycolysis proceeds within the beta-cell.
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PMID:A possible role for the adenylcyclase system in insulin secretion. 429 54

Exposure to phospholipase C increased the incorporation of [32P]Pi into phosphatidate, CMP-phosphatidate and phosphatidylinositol in rat adipose tissue and isolated adipocytes. A similar effect was observed in response to insulin and oxytocin. Theophylline, 3-isobutyl-1-methylxanthine and adenosine deaminase decreased [32P]Pi incorporation, and adenosine and N6-phenylisopropyladenosine reversed these effects. As with insulin, exposure of adipose tissue to phospholipase C stimulated oxidation of glucose, pyruvate and leucine and activated pyruvate dehydrogenase. Oxytocin and adenosine also mimicked the effects of insulin on leucine oxidation and pyruvate dehydrogenase. However, only insulin stimulated glycogen synthase activity, indicating that the regulation of synthase may be achieved by intracellular events distinct from those regulating changes in phospholipid metabolism, sugar transport and mitochondrial enzyme activities. It is postulated that exposure to phospholipase C forms diacylglycerol, which is phosphorylated to yield phosphatidate. The increased labelling of CMP-phosphatidate and phosphatidylinositol results from the conversion of phosphatidate into these lipids. The correlation between the effects of phospholipase C on phosphatidate synthesis and changes in adipose-tissue metabolism suggests the possibility that increased phosphatidate may directly or indirectly produce changes in membrane transport and enzyme activities. The pattern of phospholipid labelling produced by insulin, adenosine and oxytocin suggests that these stimuli may also increase phosphatidate synthesis, and, if so, changes in phospholipid metabolism could account for some of the metabolic actions of these stimuli.
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PMID:Phosphatidic acid and phosphatidylinositol labelling in adipose tissue. Relationship to the metabolic effects of insulin and insulin-like agents. 641 Oct 68

The dynamics of change in mitochondria-rich (MR) cells density in the skin epithelium of Bufo viridis was studied on skin biopsies taken in vivo, throughout experimental periods lasting up to 3 months. When the bathing solution contained Cl-, MR cells' density (Dmrc) greatly decreased. There was one exception, when the acclimation solution was KCl, Dmrc in the skin increased. The rate of decrease in Dmrc depended on the mode of acclimation. When bath NaCl concentration was elevated slowly in small increments, the change in Dmrc was very slow. A regression line was calculated for the rate of decrease in the density of MR cells. An equation in the form of y = 1574 - 10.23x (where x = days; R2 = 0.626) was obtained with bath NaCl that was elevated from 30 to 200 mmol/l, in 45 days. Oxytocin (60 mU/ml) increased sodium transport, independently and without effect on Cl- conductance. Theophylline (1 mmol/l), which leads also to elevation of cellular cAMP in contrast, increased Na+ transport, but elevated Cl- conductance 3-4 times as well. Cl- conductance that is activated by transepithelial potential was much lower in skin from hyperosmotic NaCl-acclimated toads, as compared with that in skin from tap water-acclimated animals. Our experiments confirm that MR cells are a major pathway for Cl- conductance, as suggested earlier. However, the density of these cells in the skin epithelium of B viridis depends not only on bath NaCl concentration, but also on the mode of acclimation of the animals. Since transport functions other than gCl reside in the amphibian skin MR cells, the density of MR cells must also depend on these functions. These functions, and the mechanisms responsible for the down and up regulation of MR cells' density, remain to be established.
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PMID:Dynamics and density of mitochondria-rich cells in toad skin epithelium. 878 20