Activation of renal mechanoreceptors increases vasopressin release in rabbits

Electrical stimulation of afferent renal nerves increases plasma vasopressin (AVP) concentration, but the role of these nerves in the control of AVP release is not known. The aim of the present study was to investigate the effect of activation of renal mechanoreceptors and chemoreceptors on plasma AVP concentration in anesthetized rabbits. Intrapelvic pressure was increased to activate renal mechanoreceptors, and the renal pelvis was perfused with 1.0 M NaCl, 0.1 M KCl, and 1.0 M mannitol solutions to activate R2 chemoreceptors. With increased pelvic pressure, plasma AVP concentration increased from 12.4 +/- 3.8 to 36.2 +/- 16.1 pg/ml at 5 min and to 37.4 +/- 16.1 pg/ml at 10 min (P less than 0.01). Plasma renin activity increased from 15.7 +/- 4.0 to 22.1 +/- 3.3 ng.ml-1.2 h-1 (P less than 0.05), but blood pressure and heart rate did not change significantly. Similar increases in plasma AVP concentration occurred during perfusion of the renal pelvis with 1.0 M NaCl (17.6 +/- 8.1 to 53.7 +/- 24.0 pg/ml), 0.1 M KCl (9.2 +/- 2.1 to 39.7 +/- 17.3 pg/ml), and 1.0 M mannitol (27.5 +/- 10.9 to 77.5 +/- 30.8 pg/ml) solutions. However, because pelvic pressure increased by 40-50 mmHg during the perfusions, the experiments were repeated with use of a different perfusion method in which pelvic pressure increased by less than 5 mmHg. Under these conditions, plasma AVP concentration did not change significantly during perfusion with any of the solutions. To determine whether the mechanoreceptor-induced increase in AVP release is mediated by the renal nerves, pelvic pressure was increased in another group of rabbits after renal denervation.(ABSTRACT TRUNCATED AT 250 WORDS)