Decreased renal blood flow in the baboon during mild dynamic leg exercise

Twelve chair-restrained baboons (Papio cynocephalus) were conditioned with operant techniques and a food reward to perform 4 min of dynamic leg exercise. During the last minute of exercise, blood flow through the left renal artery, measured by an electromagnetic flow transducer, was decreased 19 ± 2% SEM with respect to the minute of rest preceding the exercise. This response occurred within 1.5 min, was maintained throughout the exercise, and recovered to control within 2 min. Mean arterial blood pressure rose 17 ± 2%; renal vascular resistance, 46 ± 6%; heart rate, 42 ± 4%; and whole-body oxygen consumption, 233 ± 19%. Behavioral situations stimulating the arousal and feeding components of the exercise task, but not requiring muscular exertion, did not alter renal blood flow. In four animals, blood flow to the contralateral but surgically denervated kidney was measured; it increased transiently at the onset of exercise, but returned to control by the last minute of work. Thus, the baboon, like man, shows a decrease in renal blood flow during exercise. This response has a rapid onset and recovery and is primarily neurally mediated.