Blood Pressure Responses to Long-Term Avoidance Schedules in the Restrained Rhesus Monkey

Abstract

An experimental group of 6 adolescent rhesus monkeys with implanted arterial catheters was subjected to Sidman shock-avoidance schedules which lasted from 7 to 14 months after a post-training baseline period while blood pressure and pulse rate were recorded hourly. Three additional monkeys served as controls for 10- to 14-month periods; these animals showed very little cardiovascular change. Three of 4 experimental monkeys working 12 hr per day on 20-sec Sidman avoidance schedules showed a similar blood pressure response; a 4- or 5-month period of normal or hypotensive pressures was followed by a steady, monthly increase of pressure to levels that averaged 28 mm Hg systolic and 19 mm Hg diastolic higher than base line by the seventh month of the schedule. The two other experimental monkeys, on 5- and 7-sec avoidance schedules 16 hr per day, also showed marked elevations after 7 and 12 months on schedule. Pulse rate was affected variably. No consistent pathological findings were found except for atheromatous plaques surrounding the catheter tip in the abdominal aorta.