AJP - Regulatory, Integrative and Comparative Physiology, Vol 268, Issue 3 796-R807, Copyright © 1995 by American Physiological Society
In vivo diuretic actions of renal vasopressin V1 receptor stimulation in rats
C. Ledderhos, D. L. Mattson, M. M. Skelton and A. W. Cowley Jr
Institute of Physiology, Ernst Moritz Arndt-University, Greifswald, Germany.
The specific vasopressin V1 receptor agonist (V1AG;
[Phe2,Ile3,Orn8]vasopressin) was infused (2.0 ng.kg-1.min-1) into the renal
medullary interstitial space to determine the effects of selective
medullary V1 receptor stimulation on sodium and water excretion in normal
rats. Responses were compared with those of arginine vasopressin (AVP) and
vasopressin V2 receptor stimulation resulting from infusion of a V1
receptor antagonist with AVP. Medullary infusion of V1AG or AVP in
euvolemic rats produced no changes in hemodynamics or glomerular filtration
rate. V1AG increased urine flow > 60% in euvolemic rats, whereas no
change was observed with AVP. This response could not be explained by a
rise of arterial pressure or by volume retention. With V2 stimulation in
euvolemic rats, urine flow was decreased. In water diuretic rats, V1AG
produced no change, whereas AVP infusion decreased urine flow. The results
provide in vivo evidence that tubular V1 vasopressin receptor activity
results in increased urine flow and thereby modulates the antidiuretic
actions of vasopressin in the euvolemic state.
