EFFECTS OF 2, 4-DINITROPHENOL AND OUAVAIN ON RESPIRATION AND METABOLISM OF SEPARATED CEREBRAL CORTEX IN BOTH PRESENCE AND ABSENCE OF ELECTRICAL STIMULATION

Abstract

The effects of 2,4-dinitrophenol [DNP] and ouabain onthe 02 uptake, the formation of inorganic phosphate, and the production of lactic acid of the tissue slices obtained from the same rat''s cerebral cortex were investigated, both in the presence and in the absence of electrical stimulation. DNP (0.01 mM) increased the respiration and metabolism of the tissue in Na-free medium, but stimulation then had no effect; DNP in this concentration did not affect the respiration and metabolism dependent on the presence of external Na in both the unstimulated and stimulated tissues; DNP in 0.1 mM seemingly had respiratory and metabolic effects on the tissue as those of high external K. Yet, stimulation may be still effective on the adsorption of external Na toward the inside of the membrane, because the effect of the high external K differs essentially from that of DNP. Ouabain (0.5 mM) did not affect the respiration or the metabolism of the tissue without external Na. Ouabain (1 x 10-4 M and 1 x 10-6 M) hardly changed the respiration and metabolism of the unstimulated tissue in normal medium, but the respiratory and metabolic responses to stimulation were depressed as if the concentration of external Na alone was lowered without addition of ouabain. Ouabain first may inhibit the adsorption of external Na, particularly at the site when K, normally existing on the ATPase, was separated. Ouabain affected only the respiration and metabolism dependent on the existence of external Na, but DNP did not effect the action of external Na. A site of Na adsorption may be involved in the membrane ATPase.