Unmasking of the inhibitory action of glucose on insulin release after alpha 2-adrenergic activation.
Insulin release in response to glucose was measured after culture of islets from ob/ob-mice in a Ca2+-deficient medium. The stimulatory effect of 20 mM glucose disappeared after addition of 1 microM L-epinephrine, and it was reversed into inhibition when the medium contained 0.1 to 10 microM clonidine. Glucose inhibited insulin release also after activation of the alpha 2-adrenoceptors with B-HT 933, whereas blocking of these receptors with idazoxan removed glucose inhibition in the presence of clonidine. It is concluded that alpha 2-adrenergic activation provides an efficient means of unmasking the inhibitory component in the action of glucose on insulin release.
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000818:Animals; D001381:Azepines / Q000494:pharmacology; D002478:Cells, Cultured; D003000:Clonidine / Q000494:pharmacology; D004146:Dioxanes / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology*; D019329:Idazoxan; D007328:Insulin / Q000378:metabolism*; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008820:Mice, Obese
D000316:Adrenergic alpha-Agonists; D001381:Azepines; D004146:Dioxanes; D007328:Insulin; C015603:azepexole; D005947:Glucose; D003000:Clonidine; D019329:Idazoxan; D004837:Epinephrine