Attenuation of Baroreflexes During Operant Cardiac Conditioning.

Three monkeys were trained to slow and to speed heart rate on an operant schedule. After the animals were performing highly reliably they received injections of nitroglycerin or phenylephrine to elicit baro reflexes during control periods and during slowing or speeding sessions. The finding were that each animal reliably attenuated its baroreflex sensitivity and thereby avoided shock. Thus, the data showed that under appropriate behavioral conditions homeostatic adjustments of the cardiovascular system are reduced. [ABSTRACT FROM AUTHOR]