chronobiology, myocardial electrophysiology, acid-base balance, ion concetration:pentobarbital

General anaesthesia appears to disrupt cardiovascular stability by causing changes in cardiac function. The assessement of the chronobiological aspects of the pentobarbital anaesthesia impact on myocardial electrophysiology, acid-base balance and ion concentrations in a rat model was the aim of present study. The study was performed using pentobarbital- anaesthetized( 40 mg/kg, intraperitoneal) female Wistar rats adaptation to a 12h light: 12h dark (LD) cycle. Heart rate, rectal temperature, PQ interval, QT interval, QRS complex, QTc interval, and P,R and T wave amplitudes, acid-base balance and arterial concentrations of Na, K, Ca and Cl were evaluated for their dependence on the LD cycle. LD diferences were found in heart rate and rectal temperature measured before administration on of the anaesthetic agent. Results of the present study suggest that pentobarbital is probably not the most suitable anaestetic agent for chornobiological myocardial electrophysiological studies in rat models.