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)

The present study was conducted to determine the influence of dibutyryl-cAMP (dbcAMP), epinephrine, ractopamine and clenbuterol on insulin binding to porcine adipocytes. Dibutyryl-cAMP decreased insulin binding to swine adipocytes by 40 and 20% at 1.8 and 25.8 ng insulin/ml, respectively. Ractopamine and clenbuterol directly reduced insulin binding at the low insulin concentration and decreased binding at high insulin concentrations in the presence of adenosine deaminase. Scatchard analysis suggested that the reduction of insulin binding was due to a decrease in receptor number. Epinephrine alone did not influence insulin binding. In the presence of theophylline, epinephrine decreased binding at both low and high insulin concentrations; however, ractopamine plus theophylline decreased binding only at the low insulin concentration. Clenbuterol did not affect insulin binding in the presence of theophylline. Propranolol blocked the inhibitory effect of epinephrine on insulin binding. These beta-adrenergic agonists can inhibit insulin binding and, thus, antagonize insulin action in swine adipocytes.
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PMID:Decreased insulin binding to porcine adipocytes in vitro by beta-adrenergic agonists. 197 48

1. Adipocytes were isolated from the interscapular brown fat of male rats maintained at 21 degrees C. These animals were controls, streptozotocin-diabetics or 2-day insulin-treated diabetics. 2. With adipocytes from diabetic animals, maximum rates of noradrenaline-stimulated O2 uptake were decreased by 58%, and the Bmax. of [3H]GDP binding to mitochondria was decreased by 55%. Insulin administration reversed both of these changes. 3. Streptozotocin-diabetes increased basal lipolysis in adipocytes incubated with adenosine deaminase (1 unit/ml), decreased the EC50 (concn. giving 50% of maximum effect) for noradrenaline, but did not change the maximum rate of noradrenaline-stimulated lipolysis. Except for some small differences at very low concentrations (10-100 pM), diabetes or insulin treatment did not alter the sensitivity of noradrenaline-stimulated lipolysis or O2 uptake to the inhibitory effect of N6-phenylisopropyladenosine. It is therefore concluded that the lesion(s) in thermogenesis in diabetes are not attributable to any changes in lipolysis. 4. Blood flow through interscapular brown fat, measured by accumulation of [14C]DDT [14C-labelled 1,1,1-trichloro-2,2-bis-(p-chlorophenyl)ethane] was increased by 2.3-fold 70 min after a single administration of insulin to diabetic rats. This treatment decreased blood flow through epididymal white fat by 58%. 5. Propranolol treatment of diabetic rats muted the ability of insulin treatment to increase the maximum rate of noradrenaline-stimulated O2 uptake, suggesting that this action of insulin may be a secondary one rather than a direct effect of the hormone on the adipocytes.
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PMID:Factors influencing the altered thermogenic response of rat brown adipose tissue in streptozotocin-diabetes. 327 24