Influence of renal nerves on renin secretion in the conscious dog

In order to evaluate the influence of renal nerves on renin secretion during changes in blood volume, we studied the mean arterial blood pressure (MAP) and the renal venous plasma renin activity (PRA) in 6 conscious dogs having one intact and one denervated kidney. After a passive head-up tilt PRA increased significantly in the vein of the intact kidney while it remained stable in the denervated one. The intravenous injection of Furosemide (3 mg/kg) induced a rapid elevation of PRA in both renal veins. The kinetics of the variations of renin secretion were similar in the two kidneys, but its magnitude was significantly lower in the denervated side. After a slow hemorrhage of 2, 4 and 6 ml/kg, MAP was unchanged and PRA increased in both renal veins but in a significantly lower degree in the denervated side. When blood loss reached 8 ml/kg, MAP decreased and PRA increased identically in the two renal veins. It was concluded that, in conscious dogs, the renal nerves could participate in the rapid adaptations of renin secretion during small changes in the circulating blood volume.