AJP - Regulatory, Integrative and Comparative Physiology, Vol 248, Issue 2 257-R262, Copyright © 1985 by American Physiological Society
Effect of stimulation of nucleus raphe dorsalis on carotid blood flow. I. The monkey
P. J. Goadsby, R. D. Piper, G. A. Lambert and J. W. Lance
The dorsal raphe nucleus (DRN) and surrounding midbrain of 16 anaesthetized
monkeys were stimulated electrically, and carotid blood flows were measured
with electromagnetic flow probes. Stimulation of the DRN caused a
frequency-dependent decrease (vasodilatation) in both internal and external
carotid vascular resistance, which was abolished in both circulations by
bilateral section of the facial nerve intracranially. These vasodilator
responses were unaltered by intravenous administration of muscarinic
cholinergic or by alpha- or beta-adrenoceptor antagonists. A postdilatation
constrictor response, observed in the external carotid circulation, was
blocked by the alpha-adrenoceptor antagonist phentolamine. It is concluded
that projections of the DRN through the greater superficial petrosal branch
of the facial nerve mediate vasodilatation in both internal and external
carotid circulations.
