Zoletil anaesthesia in chronobiological studies

Zoletil anaesthesia does not affect vital functions; however, there is no literature evidence regarding the effect of zoletil anaesthesia on the circadian rhythm(s) of vital functions. The aims of this study, with respect to dependence on the light–dark (LD) cycle under in vivo conditions in spontaneously breathing zoletil-anaesthetized rats, were to assess ECG parameters that may to predict development of ventricular arrhythmias and to assess arterial acid–base balance, which have the direct impact on the heart electrophysiology. The experiment was performed using zoletil-anaesthetized (30 mg/kg, i.p) female Wistar rats after adaptation to LD cycle (12 h:12 h). LD differences were found in heart rate, rectal temperature, electrophysiological myocardial parameters and acid–base balance. Animals were in systemic acidosis, hypoxia and hypercapnia in the both lighted periods of the regimen day. These results suggest that zoletil can be used in chronobiological studies investigating in vivo electrophysiological myocardial properties in rat models.