Insulin-induced enhancement of uptake of noradrenaline in atrial strips.
1 Addition of insulin to the organ bath increased the force of contraction of guinea-pig left atrial strips driven electrically at 1 Hz. 2 The positive inotropic response to insulin remained unaltered in atria depleted of catecholamine or when beta-adrenoceptors were blocked by addition of propranolol to the organ bath. 3 The response os isolated atria to noradrenaline was significantly reduced in the presence of insulin. 4 Insulin affected neither the calcium accumulating abilities of the heart sarcolemma, mitochondria or microsomes, nor the cyclic adenosine 3',5'-monophosphate (cyclic-AMP)-protein kinase-induced stimulation of microsomal calcium uptake. 5 Addition of insulin to the organ bath enhanced significantly the ability of the cardiac tissue to take up [3H]-noradrenaline as well as [3H]-metaraminol. The activities of monoamine oxidase and catechol-O-methyl transferase were not changed after addition of insulin to homogenates of the heart. 6 The ability of insulin to facilitate uptake of noradrenaline would be expected to cause a decrease in the amount of the amine reaching the receptors, thus leading to a diminished response to this amine. This may explain, at least in part, insulin-induced subsensitivity to noradrenaline. 7 This view is supported by the observation that after blockade of amine uptake by destruction of nerve terminals, insulin failed to reduce the positive inotropic response to noradrenaline.
D000818:Animals; D002118:Calcium / Q000378:metabolism; D000242:Cyclic AMP / Q000494:pharmacology; D006168:Guinea Pigs; D006892:Hydroxydopamines / Q000494:pharmacology; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology*; D008297:Male; D008680:Metaraminol / Q000378:metabolism; D008861:Microsomes / Q000378:metabolism; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism*; D011494:Protein Kinases / Q000494:pharmacology; D014316:Tritium
D006892:Hydroxydopamines; D007328:Insulin; D014316:Tritium; D008680:Metaraminol; D000242:Cyclic AMP; D011494:Protein Kinases; D002118:Calcium; D009638:Norepinephrine