Distributions of VIP, substance P, neurokinin A and neurotensin in rat heart: an immunocytochemical study.

Vasoactive intestinal peptide (VIP) is a peptide amide containing 28 amino acids which was first isolated from the intestine and is distributed over the entire body but primarily in the nervous system. It is released in response to the electrical stimulation of nerve fibres, stimulation of the vagus, prostaglandin E1, oxytocin, operation stress, corticosterone. In the cardiovascular system, VIP has a vasodilation, hypotension, positive chronotropic and inotropic effects.