In vivo diuretic actions of renal vasopressin V1 receptor stimulation in rats
Ledderhos, C.; Mattson, D.L.; Skelton, M.M.; Cowley, A.W.
American Journal of Physiology 268(3 Pt 2): R796-R807
1995
ISSN/ISBN: 0002-9513 PMID: 7900923 Document Number: 450472
The specific vasopressin V-1 receptor agonist (V-1AG; (Phe-2,Ile-3,Orn-8)vasopressin) was infused (2.0 ng cntdot kg-1 cntdot min-1) into the renal medullary interstitial space to determine the effects of selective medullary V-1 receptor stimulation on sodium and water excretion in normal rats. Responses were compared with those of arginine vasopressin (AVP) and vasopressin V-2 receptor stimulation resulting from infusion of a V-1 receptor antagonist with AVP. Medullary infusion of V-1AG or AVP in euvolemic rats produced no changes in hemodynamics or glomerular filtration rate. V-1AG increased urine flow gt 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 V-2 stimulation in euvolemic rats, urine flow was decreased. In water diuretic rats, V-1AG produced no change, whereas AVP infusion decreased urine flow. The results provide in vivo evidence that tubular V-1 vasopressin receptor activity results in increased urine flow and thereby modulates the antidiuretic actions of vasopressin in the euvolemic state.