AJP - Regulatory, Integrative and Comparative Physiology, Vol 265, Issue 3 530-R536, Copyright © 1993 by American Physiological Society
Nonadrenergic noncholinergic autonomic mediation of pressor response to feeding in lambs
S. A. Jones, B. L. Langille, S. Frise and S. L. Adamson
Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada.
We examined factors mediating a 70% increase in arterial blood pressure
that occurs during feeding in newborn lambs. We report that the increase in
blood pressure during feeding was significantly reduced (to approximately
50%) and delayed in onset by combined alpha- and beta-adrenergic blockade.
Plasma angiotensin and vasopressin levels did not increase significantly
during feeding, nor was the pressor response to feeding attenuated while
using captopril to block the production of angiotensin II. Adrenalectomy or
muscarinic cholinergic blockade with atropine was also unsuccessful in
attenuating the pressor response to feeding. We demonstrated that the
component of the pressor response to feeding that was insensitive to alpha,
beta, and muscarinic blockade was mediated by the autonomic nervous system
because it was completely eliminated by ganglionic blockade with
hexamethonium. Thus nonadrenergic noncholinergic autonomic mechanisms
mediate approximately half the pressor response to feeding in lambs.
