THE EFFECT OF XENON AND NITROUS OXIDE ON IN VITRO GUINEA PIG BRAIN RESPIRATION AND OXIDATIVE PHOSPHORYLATION

¹ Department of Pharmacology, College of Medicine, State University of Iowa, Iowa City, Iowa

This study was undertaken in order to determine whether the theories postulated for the mechanism of action of barbiturate anesthesia (Bain, 1952; Brody and Bain, 1951) were applicable to the gaseous anesthetics xenon and nitrous oxide. Tissue preparations from guinea pig brain used were homogenates, mitochondria and a hash histologically similar to a slice. Substrates tested were pyruvate and glucose. Gas concentrations of both 20 per cent and 5 per cent oxygen were tested with nitrogen as the diluent. Xenon or nitrous oxide used as the diluent in both 20 per cent and 5 per cent oxygen concentration were also tested for effect on guinea pig brain oxidation of glucose. The effect of 80:20 mixtures of Xe-O₂ and N₂O-O₂ on oxidative phosphorylation was examined in homogenates and mitochondria. Experiments involving in vivo breathing of 80:20 gas mixtures and in vitro gassing with the same gas mixture were also done.

In all the techniques used no significant differences were observed among the anesthetic gases xenon, nitrous oxide, nitrogen or air in the in vitro oxidation of glucose or pyruvate or in oxidative phosphorylation by guinea pig brain tissue. It is believed, therefore, that the theories of anesthesia involving metabolic inhibition of glucose or pyruvate oxidation or the uncoupling of phosphorylation which are supported by data obtained with barbiturates are not applicable to the gaseous anesthetics xenon or nitrous oxide.