Phentolamine and the Action of Somatostatin in Man*

Abstract
The inhibition by somatostatin (SRIF) of basal and arginine-stimulated glucagon, insulin, and glucose levels was compared with that obtained when SRIF was preceded by aadrenergic blockade with phentolamine. No noteworthy differences were observed, except that the characteristic rebound of insulin upon discontinuation of SRIF was significantly lower with phentolamine (P < 0.01). These results indicate that inhibition of basal and argininestimulated glucagon and insulin secretion by SRIF in man is not mediated through activation by a-adrenergic receptors.