Changes in control of renin release in congestive heart failure in dogs: response to acute and chronic vasodilator therapy.

Neural control of renin secretion is an important physiologic mechanism, but alterations in the central nervous system feedback and control of renin release in heart failure have not been investigated. Accordingly we studied conscious dogs after volume overload (arteriovenous fistula) or chronic myocardial infarction. Acute infusion of nitroprusside was used to test the renin response to arterial hypotension and decreased central blood volume. Hydralazine and prazosin administration were used to test the response to chronic vasodilator administration. After 4 weeks of volume overload or 3 weeks after myocardial infarction, the renin response to a graded hypotensive stimulus was blunted. After 7 days of hydralazine or prazosin administration, plasma renin activity remained elevated and blood volume increased from baseline values. Our results indicate a decrease in the neural feedback control of renin release after chronic volume overload or myocardial infarction. However, chronic vasodilator administration still resulted in sustained augmented renin secretion and an increase in blood volume.