Interaction between neural and nonneural mechanisms controlling renin secretion rate.

The interaction between the neural and nonneural mechanisms in the control of renin secretion rate was studied in anesthetized vagotomized dogs at renal arterial pressures of 170, 130, 90, and 50 mmHg. Left renal nerves were stimulated (RNS) at either 0.075, 0.3, or 0.7 Hz and the right kidney was denervated. At spontaneous renal arterial pressure RNS at 0.075, 0.3, and 0.7 Hz decreased renal blood flow 0, 1 +/- 0, and 2 +/- 1%, respectively, and urinary sodium excretion 0, 2 +/- 1, and 22 +/- 3%, respectively. RNS at 0.075 Hz augmented renin secretion rate at 50 mmHg by 1,806 +/- 505 ng/min; there was no augmentation at 90, 130, and 170 mmHg. RNS at 0.3 Hz augmented renin secretion rate at 50 and 90 mmHg by 2,635 +/- 824 and 1,197 +/- 289 ng/min, respectively; there was no augmentation at 130 and 170 mmHg. RNS at 0.7 Hz augmented renin secretion rate at 50, 90, and 130 mmHg by 1,421 +/- 287, 747 +/- 172, and 273 +/- 163 ng/min, respectively; there was no augmentation at 170 mmHg. RNS at 0.075 Hz to one kidney and 0.7 Hz to the other kidney in the same dog demonstrated that the renin secretion rate was greater with RNS at 0.7 Hz than with 0.075 Hz at 50 and 90 mmHg but not at 130 and 170 mmHg. We conclude that the nonneural and neural mechanisms interact in the control of renin secretion rate. The degree of interaction depends on the level of renal arterial pressure and the intensity of RNS.