Catecholamine inhibition of Ca2+-induced insulin secretion from electrically permeabilised islets of Langerhans.
Noradrenaline (1-10 microM) inhibited Ca2+-induced insulin secretion from electrically permeabilised islets of Langerhans with an efficacy similar to that for inhibition of glucose-induced insulin secretion from intact islets. The inhibition of insulin secretion from permeabilised islets was blocked by the alpha 2-adrenoreceptor antagonist, yohimbine. Adenosine 3',5'-cyclic monophosphate (cAMP) did not relieve the noradrenaline inhibition of Ca2+-induced secretion from the permeabilised islets, although noradrenaline did not affect the secretory responses to cAMP at substimulatory (50 nM) concentrations of Ca2+. These results suggest that catecholamines do not inhibit insulin secretion solely by reducing B-cell adenylate cyclase activity, and imply that one site of action of noradrenaline is at a late stage in the secretory process.
D000818:Animals; D003994:Bucladesine / Q000037:antagonists & inhibitors; D002118:Calcium / Q000037:antagonists & inhibitors*; D002395:Catecholamines / Q000494:pharmacology*; D000242:Cyclic AMP / Q000037:antagonists & inhibitors; D004558:Electric Stimulation; D005947:Glucose / Q000037:antagonists & inhibitors; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects* / Q000378:metabolism; D009638:Norepinephrine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D010539:Permeability; D051381:Rats; D015016:Yohimbine / Q000494:pharmacology
D002395:Catecholamines; D007328:Insulin; D015016:Yohimbine; D003994:Bucladesine; D000242:Cyclic AMP; D005947:Glucose; D002118:Calcium; D009638:Norepinephrine