Electrical stimulation of paraventricular nucleus increases plasma renin activity

Studies employing direct electrical stimulation of the renal nerves have shown that, depending on the frequency used, selective effects on renal function can be evoked. With low frequencies, an increase in renin secretion can be elicited without affecting glomerular filtration rate, sodium excretion, or renal blood flow. In the present investigation the possibility was addressed that the central nervous system (CNS) is also organized to evoke selective changes in renal function. The paraventricular nucleus (PVN) of the hypothalamus was electrically stimulated in conscious rats with 150 microA and frequencies of 2.5, 5, 10, and 15 Hz. Blood samples for determination of plasma renin activity (PRA) were collected before and at the end of each 5-min stimulation period. The lower frequencies had no effect on PRA, but stimulation with 10 and 15 Hz produced a significant increase. This effect on PRA was not accompanied by changes in arterial pressure or renal blood flow. In a separate group of animals, stimulation of the PVN with 15 Hz produced a marked decrease in urine volume, but sodium excretion did not change. These data raise the possibility that the CNS is organized to evoke selective increases in sympathetic outflow to the kidney and to produce separate changes in renal functions.