Role of renal nerves in regulation of vasopressin secretion and blood pressure in conscious rabbits

Abstract

The observation that electrical stimulation of the renal nerves increases vasopressin secretion raises the possibility that the renal nerves may participate in the control of vasopressin secretion. In the present investigation, the effects of renal denervation on the vasopressin response to two reflex stimuli (nitroprusside infusion and hemorrhage) and two osmotic stimuli (hypertonic saline infusion and water deprivation) were studied in conscious, chronically prepared rabbits. Nitroprusside infusion in 13 intact and 14 denervated rabbits caused similar decreases in mean arterial pressure (MAP) and the increase in plasma arginine vasopressin concentration (PAVP) in intact (2.6 +/- 0.3 to 5.8 +/- 0.9 pg/ml, P less than 0.01) and denervated (2.8 +/- 0.3 to 5.7 +/- 1.3 pg/ml, P less than 0.01) rabbits was not significantly different. Hemorrhage (20 ml/kg) in 15 intact and 14 denervated rabbits caused similar decreases in MAP. Again, the increase in PAVP from 2.7 +/- 0.3 to 159.0 +/- 37.1 pg/ml (P less than 0.01) in intact and from 5.0 +/- 1.7 to 115.4 +/- 45.6 pg/ml (P less than 0.01) in denervated rabbits was not significantly different, nor was the relationship between PAVP and MAP in the two groups. In seven intact rabbits, hypertonic saline infusion increased PAVP from 4.0 +/- 0.9 to 10.9 +/- 2.8 pg/ml (P less than 0.05). The change in six denervated rabbits was not significantly different, nor was the relationship between PAVP and plasma osmolality. During water deprivation (24 h) in six intact rabbits, PAVP increased from 4.0 +/- 0.7 to 6.9 +/- 0.6 pg/ml (P less than 0.05). Again, the increase in PAVP in six denervated rabbits was not significantly different from that in the intact rabbits. The change in MAP during water deprivation in the two groups was also not significantly different. Renal cortical norepinephrine concentration in denervated kidneys was less than 10 ng/g wet wt. These results indicate that, in conscious rabbits, renal denervation does not impair the osmotic or reflex regulation of vasopressin secretion, nor does it interfere with blood pressure regulation during hypovolemia or hypotension.