AJP - Heart and Circulatory Physiology, Vol 244, Issue 3 351-H356, Copyright © 1983 by American Physiological Society
Compensatory response to hemorrhage in conscious dogs on normal and low salt intake
R. I. Kopelman, V. J. Dzau, S. Shimabukuro and A. C. Barger
The compensatory response to moderately severe hemorrhage (30 ml/kg) was
studied in chronically catheterized conscious dogs maintained on normal and
low salt intake. Although the fall in blood pressure and the increase in
heart rate were similar in the two salt states, the salt-restricted animals
had significantly greater rises in plasma renin activity and plasma
catecholamines following hemorrhage than did the normal salt dogs. To
compare further the relative roles of the alpha-adrenergic system and the
renin-angiotensin system in the maintenance of blood pressure following
hemorrhage, pharmacologic blockade with either phentolamine or converting
enzyme inhibitor was performed 20 min after the completion of the
hemorrhage. These latter experiments demonstrated that salt restriction
resulted in a significantly greater role for the renin-angiotensin system.
Moreover, interruption of the renin-angiotensin system blunted the
anticipated rise in catecholamines and heart rate during the additional
hypotension induced by converting enzyme blockade after hemorrhage.
