The determination of alpha-adrenergic receptor concentration on rat pancreatic islet cells

The selective alpha 2 adrenergic antagonist yohimbine has been shown to prevent the noradrenaline induced inhibition of insulin secretion from isolated rat islets of Langerhans. Binding studies utilizing [3H]yohimbine showed specific binding to dispersed rat islet cells with a Kd of 2.9 nM and receptor concentration of 645 fmols/mg protein. The use of chloroquine to inhibit receptor recycling did not affect binding of the ligand. Binding studies and secretion data are consistent with the suggestion that adrenergic receptors of the alpha 2 sub-type may play a dominant role in the regulation of insulin secretion.