AJP - Heart and Circulatory Physiology, Vol 256, Issue 1 101-H104, Copyright © 1989 by American Physiological Society
Pressor responses to vasopressin in pigs and sheep with DOCA hypertension
W. D. Ling, D. P. Brooks, J. T. Crofton, L. Share and D. F. Bohr
Department of Physiology, University of Tennessee, Memphis 38263.
Pressor responses to vasopressin were determined in pigs and sheep during
three experimental periods: 1) before deoxycorticosterone acetate (DOCA)
treatment, 2) 21 days after DOCA implantation (100 mg/kg) when a stable
hypertension had developed, and 3) after reversal of the hypertension by
removing the implant in the sheep or by decreasing the dietary sodium
intake in the pigs. The infusion of lysine (LVP) or arginine (AVP)
vasopressin into pigs and sheep, respectively, resulted in dose-dependent
increases in plasma vasopressin concentration. The levels of plasma LVP or
AVP achieved by these infusions were not altered in any of the experimental
periods. The administration of vasopressin resulted in dose-dependent
increases in mean arterial blood pressure. However, pigs required five
times more LVP than sheep required AVP to achieve similar pressor
responses. The pressor responsiveness to vasopressin was attenuated when
either species was made hypertensive. This effect was reversed when normal
blood pressure was restored by reducing sodium intake in the pigs or by
removing the DOCA implant from the sheep. These data establish that an
increased pressor response to vasopressin does not contribute to DOCA
hypertension in pigs or sheep.
