Sympathetic adrenergic blockade effects upon operantly conditioned blood pressure elevations in baboons.

Sympathetic adrenergic nervous activity during operantly conditioned hypertension was evaluated by assessing the effects of specific alpha-(phentolamine or phenoxybenzamine) and beta- (propranolol) adrenergic blockers in baboons reinforced for increasing diastolic pressure in daily, 12-h sessions. In the first 10 min of control (no blockade) sessions, mean heart rate increased 24 bpm (21%) above the value for the 10 min immediately prior to the beginning of the sessions; systolic pressure increased 27 mm Hg (22%) and diastolic pressure increased 24 mm Hg (31%). Betablockade eliminated the tachycardia but did not attenuate the increased blood pressure. Alpha-blockade did not attenuate the increased blood pressure significantly either. Combined alpha- and beta-blockade did significantly attenuate the increase in diastolic pressure, but consistent, significant increases in systolic pressure (17 mm Hg, 17%) and diastolic pressure (16 mm Hg, 26%) still occurred. The results support the participation of the sympathetic adrenergic nervous system in producing operantly conditioned blood pressure changes, but the results are also consistent with the additional participation of nonadrenergic factors in operantly conditioned hypertension.