Transient postocclusive renal vasospasm in conscious rhesus monkeys

Transient postocclusive renal vasospasm occurred in nine conscious postoperative monkeys with electromagnetic flowmeters implanted on the left renal artery. During an interval of 5-7 days, beginning approximately 1 wk after the implantation of an electromagnetic flowmeter and pneumatic occlusive cuff on the renal artery, occlusions produced by 2- to 15-s inflations of the cuff were invariably followed by flow reduction of 40%-90%, which began 30-60 s after occlusion and lasted from 3 to 60 min. These flow reductions were not related to changes in heart rate, cardiac output, blood pressure, nor to flow in other branches of the aorta; nor were they affected by papaverine (5 mg/kg), propranolol (1 mg/kg), phentolamine (3-5 mg/kg per min), or dipyridamole (1 mg/kg). This response to renal artery occlusion disappeared after 5-7 days and did not recur. This phenomenon should be kept in mind when planning experiments involving long-term implantation of flowmeters on the renal arteries of monkeys.