AJP - Heart and Circulatory Physiology, Vol 249, Issue 1 29-H33, Copyright © 1985 by American Physiological Society
Hemodynamic effects of arginine vasopressin in conscious water-deprived rats
W. Rascher, H. Meffle and F. Gross
By means of a specific antagonist [d(CH2)5AVP] of the vasoconstrictor
activity of arginine vasopressin (AVP), we studied whether the
vasoconstrictor effect of AVP contributed to the blood pressure control
during water deprivation in conscious rats. After 24 h of dehydration
plasma AVP rose from 3.5 +/- 0.5 to 11.2 +/- 2.0 fmol/ml. Intravenous
injection of 5 micrograms/kg d(CH2)5AVP reduced total peripheral
resistance. Since cardiac output rose simultaneously, mean arterial blood
pressure remained unchanged. In rats with sinoaortic deafferentation (SAD)
4 wk before water deprivation, d(CH2)5AVP caused a reduction of total
peripheral resistance and of mean arterial pressure, whereas cardiac output
remained unchanged. Consequently, mean arterial pressure fell. No
hemodynamic changes were observed in hydrated control rats with and without
SAD. It is concluded that the vasoconstrictor activity of AVP plays an
important role in maintaining blood pressure during water deprivation in
conscious rats. After AVP blockade, arterial pressure fell only in SAD rats
as intact rats maintain arterial pressure via acute increase cardiac
output.
