EFFECTS OF ANESTHESIA ON CARDIAC AND RENAL SYMPATHETIC-NERVE ACTIVITIES AND PLASMA-CATECHOLAMINES

The effects of pentobarbital and chloralose on cardiac sympathetic ner ve activity (CSNA), renal sympathetic nerve activity (RSNA), arterial pressure (AP), and heart rate (HR) were examined using conscious cats. Arterial blood was sampled intermittently to measure plasma epinephri ne. Pentobarbital (25-30 mg/kg iv) decreased CSNA, RSNA, AP, and HR. T he reduction of CSNA (71 +/- 7%) was larger and lasted longer than tha t of RSNA (33 +/- 12%). Chloralose (40-50 mg/kg iv) decreased CSNA 66 +/- 9% and HR, increased RSNA 127 +/- 122%, and did not affect AP. The baroreflex relationship between AP and CSNA was examined by increasin g AP to 145 mmHg and decreasing AP to 55 mmHg. Both pentobarbital and chloralose shifted the AP-CSNA relationship curve downward and blunted the slope of the curve, indicating that both drugs attenuate tonic an d baroreflex cardiac sympathetic outflow. Pentobarbital and chloralose reduced plasma epinephrine, suggesting a decrease in adrenal sympathe tic nerve activity. It is concluded that pentobarbital or chloralose a ffects differentially sympathetic outflows to different organs such as the heart, kidney, and adrenal gland.