Extracranial vasodilation mediated by vasoactive intestinal polypeptide (VIP).

Pooled antisera to vasoactive intestinal polypeptide were used to block neurogenic extracranial vasodilatation elicited from either brainstem (locus coeruleus) or pterygopalatine ganglion stimulation in the cat. Vasodilatation was not inhibited by sham immune sera, or by antisera to bradykinin or substance P. The efferent pathway for vasodilatation from the locus coeruleus traverses the facial nerve (greater superficial petrosal branch) and the pterygopalatine and otic ganglia. Its blockade demonstrates a novel action of a peptide transmitter in the expression of a central neurogenic response.