Hemodynamic adjustments during free-operant avoidance in dogs with unilateral renal artery stenosis.

To examine blood pressure (BP) and heart rate (HR) during avoidance performance in animals with renal artery stenosis, 10 dogs were prepared with arterial catheters, and subsequently underwent habituation to the experimental apparatus. Following this, 6 of the dogs received ligation of the left renal artery to reduce luminal dia. 50–80%, and habituation was repeated in all dogs. After training on a free-operant avoidance task, the animals were exposed to 5 daily 60 min avoidance sessions consisting of alternating 5 min periods of non-avoidance and avoidance. On 2 days, the dogs received either propranolol (0.3 mg/kg) or phenoxybenzamine (1.0 mg/kg) intra-arterially during the second nonavoidance period. While stenosis of the renal artery was effective in increasing diastolic BP during the second habituation exposure, a permanent BP elevation was not observed. These animals displayed similar pressor responses but larger HR increases than controls during the first and final avoidance periods. Drug effects were minimal. The results suggest that an exaggerated tachycardia may characterize the hemodynamic adjustment to environmental challenges in animals with unilateral renal artery stenosis, as it does in some hypertensive patients.