Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.5.4.4 (adenosine deaminase)
 5,136 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In rat adipocytes, the breakdown of phosphoinositides labelled by a 3 h incubation with [3H]inositol resulted in the accumulation of labelled inositol mono-, bis- and trisphosphates in the presence of oxytocin, vasotocin or vasopressin. Oxytocin at a concentration of 1 nM markedly increased phosphoinositide breakdown. Incubation of adipocytes both during the 3 h labelling and the 10 min breakdown period in a low adenosine medium (presence of adenosine deaminase) or high adenosine medium (presence of 0.1 microM N6-(phenylisopropyl)adenosine) (PIA) did not affect basal or ligand-stimulated phosphoinositide breakdown. The addition of 1 microM PIA only during the measurement of phosphoinositide breakdown variably stimulated basal breakdown but significantly potentiated that due to oxytocin. Isoproterenol similarly had little effect on basal but inhibited oxytocin stimulation of phosphoinositide breakdown. Insulin did not affect basal or ligand-stimulated phosphoinositide breakdown in the low or high adenosine medium. However, in adipocytes incubated in the absence of added adenosine deaminase or PIA, insulin stimulated basal accumulation of inositol phosphates by about 20% and inhibited that due to oxytocin by about 20%. There was no significant effect of insulin on the stimulation by vasopressin or vasotocin of phosphoinositide breakdown. These results indicate that, in adipocytes, phosphoinositide breakdown stimulated by oxytocin is enhanced by adenosine, inhibited by isoproterenol and, under some conditions is inhibited by insulin.
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PMID:Regulation of oxytocin-induced phosphoinositide breakdown in adipocytes by adenosine, isoproterenol and insulin. 255 83

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