Mechanisms controlling renal blood flow in the baboon during acute emotional stress

Renal blood flow in normal and denervated kidneys, heart rate, arterial blood pressure, 0₂ consumption, and terminal aortic blood flow were recorded from baboons (Papio cynocephalus) maintained in primate restraint chairs. A conditional emotional response (CER) was produced by presenting a one-minute auditory signal followed by a brief, 7-10 ma shock. The conditional cardiovascular responses began to appear at about the 5th training trial and were stable by the 10th. Renal blood flow decreased 30-60% within 2 seconds, recovered to normal levels by the 5th second, and dropped again at about the 8th second. The second decrease was 15-25% and was maintained for the duration of the minute. Blood pressure, heart rate, and aortic flow were elevated during the CER. The responses were consistent both between and within individuals. Blood flow in denervated kidneys failed to show the initial decrease, but continued to show a modified second drop. Vasoconstrictor drugs produced a decrease in renal flow beginning about 8 seconds after intravenous injection. These results suggest that during acute emotion there is a rapid, neurally mediated renal vasoconstriction followed by a later, long lasting mixed neurally and humorally mediated vasoconstriction.