HEART RATE AND BLOOD PRESSURE RESPONSES TO SIGNALED AND UNSIGNALED SHOCKS - EFFECTS OF CARDIAC SYMPATHECTOMY

Curarized and subjected 12 normal and cardiac sympathectomized dogs to either signaled or unsignaled shocks. The unsignaled shocks were of several intensities and durations. There were no differences between signaled and unsignaled shocks in their effects on heart-rate, systolic, and diastolic blood-pressure responses. Following the termination of shocks shorter than 5 sec., and during shocks longer than 5 sec., heart rate decreased while blood-pressure indices increased. Heart rate fell below base-line levels directly after stimulus termination although blood-pressure indices were still elevated. This deceleratory overshoot increased over trials of signaled shock in all sympathectomized Ss. Such functional differences between heart rate and blood pressure preclude the strong inference that heart rate is a direct measure of sympathetic activation. (29 ref.) (PsycINFO Database Record (c) 2006 APA, all rights reserved). © 1969 American Psychological Association.