The aim of study was to review the status of arterial pH, pO(2) and pCO(2) under general anesthesias in dependence on the light-dark (LD) cycle in spontaneously breathing rats. The experiments were performed using three- to four-month-old pentobarbital(P)-, ketamine/xylazine(K/X)- and zoletil(Z)-anesthetized female Wistar rats after a four-week adaptation to an LD cycle (12 h light:12 h dark). The animals were divided into three experimental groups according to the anesthetic agent used: P (light n=11; dark n=8); K/X (light n=13; dark n=11); and Z (light n=18; dark n=26). pH and blood gases from arterial blood were analyzed. In P anesthesia, LD differences in pH, pO(2), and pCO(2) were eliminated. In K/X anesthesia, parameters showed significant LD differences. In Z anesthesia, LD differences were detected for pH and pO(2) only. Acidosis, hypoxia, and hypercapnia have been reported for all types of anesthesia during the light period. In the dark period, except for P anesthesia, the environment was more stable and values fluctuated within normal ranges. From a chronobiological perspective, P anesthesia was not the most appropriate type of anesthesia in these rat experiments. It eliminated LD differences, and also produced a more acidic environment and more pronounced hypercapnia than K/X and Z anesthesias.

Department of Physiology and Pathophysiology Medical Faculty Ostrava University Ostrava Czech Republic

Department of Physiology Medical Faculty Pavol Josef Šafárik University Slovak Republic

Laboratory of Research Bio models Medical Faculty Safarik's University Kosice Slovak Republic

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