The effect of insulin-induced hypoglycemia with and without atropine on plasma vasoactive intestinal polypeptide in man.

Plasma vasoactive intestinal polypeptide (VIP) was measured in six healthy male students on 2 separate days after insulin-induced hypoglycemia with and without atropine and on a 3rd day in five of the students after atropine alone. A significant increase in peripheral plasma VIP was observed when atropine was given together with insulin, whereas insulin or atropine alone had no effect on plasma VIP. It is suggested that cholinergic nicotinic receptors may be involved in the increase of VIP after insulin-induced hypoglycemia and that the lack of VIP increase seen after insulin alone may be caused by an inhibitory effect of other gastrointestinal hormones.