Effects of Arginine Vasopressin on Blood Pressure and Renal Prostaglandin E₂ in Rabbits

抄録

The role of arginine vasopressin (AVP) in blood pressure regulation in humans and animals is still controversial. The present study was designed to investigate the effects of AVP on blood pressure and the excretion of sodium and prostaglandin (PG) E₂ in rabbits. AVP dissolved in 0.01 M acetic acid was infused subcutaneously at a rate of 0.86 ng/kg/min with a miniosmotic pump into 12 New Zealand white rabbits (2.7±3.4 kg), while 10 controls were given vehicle alone. AVP infusion resulted in a 3.5-fold rise in the level of plasma AVP (21.8±4.4 (SEM) pg/ml) as compared with controls, associated with a signifcant decrease in the urine volume and urinary excretion of sodium. The PGE₂ excretion was increased 1.8-fold after AVP infusion. In the chronic AVP-infused group, blood pressure was not significantly increased, but the acute vascular response to AVP was significantly attenuated without any changes in the vasopressor response to angiotensin II. Preadministration of V₁-antagonist completely abolished the vasopressor action of AVP, but not that of angiotensin II, in either group. These results suggest that circulating AVP within physiological range of concentrations may stimulate renal PGE₂ synthesis and attenuate the vascular response through vascular V₁ receptors without affecting the baroreflex, which may be attenuated through V₂ receptors.