Evaluation of the effect of pentobarbitone anaesthesia on the plasma potassium concentration in the rabbit and the dog.

The purpose of these studies was to determine the reasons for the hypokalaemia observed in rabbits studied in our laboratory. The rabbits consumed standard rabbit chow which is rich in potassium and remained in potassium balance. Hypokalaemia was only observed following anaesthesia. A number of additional investigations were undertaken to clarify the mechanisms involved. The hypokalaemia could not be attributed to technical factors, alkalaemia, hyperinsulinaemia or hyperaldosteronism, but seemed to be a function of anaesthesia. This effect of pentobarbitone anaesthesia was not unique to the rabbit, as similar changes also occurred in the anaesthetized dog. The findings reported in this paper have significant implications with respect to the interpretation of plasma potassium concentrations in anaesthetized subjects or animals.