RIGHT CORONARY AUTOREGULATION IN CONSCIOUS, CHRONICALLY INSTRUMENTED DOGS

Right coronary (RC) autoregulation and right ventricular (RV) function were assessed in conscious dogs, chronically instrumented to measure RC flow and RC pressure (RCP) as a hydraulic occluder on the RC was in flated. Dogs were then anesthetized, and RC autoregulation and RV func tion were again assessed. In the conscious state, moderate RC autoregu lation was present with closed loop gains (G(c)) of 0.59-0.27 as RCP w as reduced from 100 to 40 mmHg. In the anesthetized state, G(c) was no t significantly less than in the conscious state at RCP >50 mmHg. The range and potency of RV autoregulation were greater in both groups tha n for previously reported findings in anesthetized dogs with RC perfus ed by an extracorporeal system. RV contractile function was well maint ained in conscious and anesthetized dogs at RCP >45 mmHg. We conclude the following: 1) modest RC autoregulation is present in the conscious dog, 2) anesthesia limits the range but not the degree of RC autoregu lation, 3) extracorporeal perfusion systems appear to depress RC autor egulation, and 4) RV contractile function remains constant in both con scious and anesthetized dogs until RCP falls below 50 mmHg.