AJP - Regulatory, Integrative and Comparative Physiology, Vol 262, Issue 2 276-R283, Copyright © 1992 by American Physiological Society
Patterns of hemodynamic responses associated with central activation of coronary vasoconstriction
L. F. Jones, D. D. Gutterman and M. J. Brody
Department of Pharmacology, University of Iowa, Iowa City 52242.
Previous studies in our laboratory have identified several central sites
from which coronary vasoconstriction can be elicited by electrical
stimulation. The present study was conducted to determine if specific
patterns of hemodynamic responses are associated with activation of the
coronary vasoconstrictor pathway in the hypothalamus, pons, and medulla.
Cats anesthetized with chloralose were instrumented for recording arterial
pressure, heart rate, and coronary, femoral, renal, and mesenteric blood
flow velocities. After vagotomy and atenolol (1 mg/kg iv), anterior
hypothalamus (AHA), parabrachial nucleus (PBN), a site very close to the
ventral surface of the pons lateral to the pyramidal tract, and rostral
ventrolateral medulla (RVLM) were stimulated electrically. Stimulation
produced a decrease in coronary blood flow that was associated with all of
the cardiovascular components of the defense reaction, an integrated
response that included a decrease in hindquarter vascular resistance
(blocked by methyl atropine), increases in renal and mesenteric vascular
resistances, and a pressor response, except no change in renal vascular
resistance from RVLM. Different patterns of hemodynamic responses were
obtained from sites outside the coronary vasoconstrictor areas. From these
results we conclude that coronary vasoconstriction is a frequent component
of the defense reaction.
