AJP - Regulatory, Integrative and Comparative Physiology, Vol 267, Issue 6 1467-R1471, Copyright © 1994 by American Physiological Society
Chronic and selective vasopressin blockade in spontaneously hypertensive rats
H. Okada, H. Suzuki, Y. Kanno, Y. Yamamura and T. Saruta
Department of Internal Medicine, School of Medicine, Keio University, Tokyo, Japan.
Chronic effects of orally available, nonpeptide vasopressin V1 and V2
receptor antagonists on conscious spontaneously hypertensive rats (SHR)
were investigated. SHR and Wistar rats were divided into four groups,
groups S-1 to S-4 and W-1 to W-4, respectively. Groups S-1 and W-1 were
untreated as control. Groups S-2 and W-2 were treated with V1 antagonist,
groups S-3 and W-3 received V2 antagonist, and groups S-4 and W-4 were
treated with both of V1 and V2 antagonists. V1 and/or V2 antagonists did
not affect degree of blood pressure of W-2, W-3, and W-4 rats, and V1
antagonist, alone or combined with V2 antagonist, slightly reduced
increases in blood pressure of S-2 and S-4 rats without significance.
However, V2 antagonist induced significantly massive and hyposmolar urine
in W-3 rats compared with that in S-3 rats. In conclusion, in SHR,
circulating vasopressin contributes to increases in blood pressure via
either V1 or V2 receptors less than expected from previous studies with
antibodies or peptide antagonists.
