The effect of infusion of various peptide antisera on vasodilatation in the cat common carotid vascular territory.

Electrical stimulation of the locus coeruleus leads to a frequency-dependent vasoconstriction in the internal carotid vascular bed and a frequency-dependent vasodilatation in the external carotid vascular bed. This latter dilator response is mediated via the facial nerve, and then more peripherally through the pterygopalatine and otic ganglia, and employs the neuropeptide vasoactive intestinal polypeptide (VIP) as its transmitter.