Much information concerning the mechanisms of cell respiration has been obtained through the use of narcotics, such as the barbiturates, urethane and chloretone. These substances in general inhibit respiratory processes and show a certain selectivity of action (cf. Quastel, '39).
Recently a new series of compounds, the 5,5-dialkyl-2,4-oxazolidineiones, has been synthesized and studied pharmacologically by Stoughton ('41). These compounds are structurally related to the barbiturates and the hydantoinates and like most of these are central nervous system depressants. Of this series the di-n-propyl derivative, propazone, has been investigated most extensively (Stoughton and Baxter, '41 ; Luton, Blalock, Baxter and Stoughton, '41). Certain of the properties of propazone make it especially suitable f o r in vitro investigation by manometric methods. For example, the sodium salt is very soluble in water and approximately neutral in reaction, in contrast to the quite alkaline reaction of the sodium salts of some barbiturates and of diphenyl hydantoinate. Furthermore, we have shown in a preliminary communication that relatively low concentrations of propazone sodium inhibit the oxygen consumption of rat brain, kidney and liver in vitro, and that such inhibition is a t least 70% reversible in the case of kidney (Fuhrman and Field, '42 a). A more detailed analysis of the action of propazone on the metabolism of excised rat cerebral cortex is reported in the present paper.
Methods
Forty-six adult male albino rats were used. The brain was removed immediately after decapitation and transferred to a moist chamber maintained at 35" C. f o r slicing. Cerebral cortex slices, cut with a razor blade guided by a lucite template (cf. Crismon and Field, '40) were 'โฌ$upported by grants from tile John and Mary R. Markle Foundation and from the Fluid Research Fund of Stanford Univeraity Medical School.