AJP - Heart and Circulatory Physiology, Vol 234, Issue 1 67-H73, Copyright © 1978 by American Physiological Society
Hemodynamic similarities between the trigeminal and aortic vasodepressor responses
M. Kumada, R. A. Dampney, M. H. Whitnall and D. J. Reis
The hemodynamic changes associated with hypotension elicited by electrical
stimulation of the spinal trigeminal complex (trigeminal depressor
response, TDR) or the aortic nerve (aortic depressor reflex, ADR) were
compared in rabbits anesthetized with urethan. The hypotension associated
with each response was accompanied by bradycardia, a marked fall in total
peripheral resistance, a small decrease in cardiac output, and a nonuniform
decrease in regional vascular resistances, with the order of magnitude of
the decrease being femoral greater than mesenteric greater than renal
arterial resistance. In individual experiments the percent decrease in
heart rate, total peripheral resistance, or regional resistances was
plotted against the percent fall in arterial pressure to obtain a pair of
regression lines during the TDR and ADR. There was no significant
difference in the slope or y-intercept of the regression line between the
TDR and ADR for all of the hemodynamic variables examined. In both
responses, however, the slope of the femoral resistance/arterial pressure
relationship was significantly greater than that of the renal
resistance/arterial pressure relationship. We conclude that the TDR is
characterized by a pattern of hemodynamic changes similar to that of the
ADR.
