Adrenergic inhibition of insulin secretion involves pertussis toxin-sensitive and -insensitive mechanisms.

We studied the involvement of Bordetella pertussis toxin (PTX)-sensitive G proteins in the inhibition by adrenaline of insulin secretion from the isolated rat pancreas. The -90% inhibition induced by adrenaline (0.05 microM) was partially abolished after in vivo PTX pretreatment. The residual inhibitory effect of adrenaline in PTX-pretreated rats was suppressed by the alpha 2-adrenoceptor antagonist, yohimbine, but was not modified by the alpha 1-adrenoceptor antagonist, prazosin. Thus, the alpha 2-inhibitory effect of adrenaline on B-cells is mediated by both PTX-sensitive and PTX-insensitive mechanisms.