The Effects of Conflict on Tonic Levels of Blood Pressure in the Genetically Borderline Hypertensive Rat

Studies of aversive conditioning in animals have seldom elicited tonic elevations in blood pressure (BP) equivalent to those which produce pathological changes in humans. While it is possible that psychological factors are not that important in the etiology of hypertension, it is also possible that the failure to elicit large tonic elevations in BP in animals may be due either to stressors which are insufficiently potent and/or to an inadequate physiological model. The present study sought to maximize the probability of producing large tonic changes in BPs by using a conflict paradignt in a genetic strain of rats which develops systolic BPs in the borderline hypertensive area (c. 150 mmHg). Forty‐eight male F 1 generation offspring of spontaneously hypertensive rats mated with normotensive controls were randomly split into three groups: experimental (subjected to 3 weeks of avoidance training and 12 weeks of conflict in conditioning cages), mild restraint control (placed in conditioning cages daily but not shocked), and maturation control (neither shocked nor restrained) groups. Animals subjected to conflict gradually developed tonic levels of systolic BP well into the hypertensive range (c. 185 mmHg). Restraint control animals also showed some elevation (c. 165 mmHg), but maturational controls showed no change (c. 150 mmHg). The saliency of this animal model for the study of stress‐induced hypertension is discussed.