The Control of Oxidative Phosphorylation in the Adrenal Gland (Y1) Cell Line
We determined the proportion of oxygen consumption due to oxidative phosphorylation by mitochondria in an adrenal gland cell line (Y1 cells). In addition we determined the relative proportion of in situ mitochondrial oxygen consumption attributable to (i) proton leak and (ii) ATP turnover in these cells. This approach allowed use of top-down elasticity analysis to determine control of oxidative phosphorylation by mitochondrial (a) proton leak flux (b) substrate oxidation flux and (c) ATP turnover flux, as a function of changes in in situmitochondrial membrane potential. Our data show that resting oxygen consumptions rates of Y1 cells to be 87±7 nmolO/min/107 cells of which 38±3% was not due to oxidative phosphorylation. We demonstrated that mitochondrial proton leak accounted for 7±3% of total cellular oxygen consumption or 12±6% of resting mitochondrial oxygen consumption, with ATP turnover accounting for 55±3% of total cellular oxygen consumption or 78±6% of mitochondrial oxygen consumption. Control of resting mitochondrial oxygen consumption in Y1 cells was shared by (a) substrate oxidation flux (37±8%), (b) proton leak flux (15±8%) and (c) ATP turnover (56±8%). Our data demonstrate, for the first time, that the majority of oxygen consumption by resting Y1 cells is due to oxidative phosphorylation.
KeywordsOxygen Consumption Oxidative Phosphorylation Mitochondrial Membrane Potential Oxygen Consumption Rate Proton Leak
Unable to display preview. Download preview PDF.
- 1.D.F.S. Rolfe, A.J. Hulbert and M.D. Brand, Characteristics of mitochondrial proton leak and control of oxidative phosphorylation in the major oxygen-consuming tissues of the rat, Biochim. Biophys. Acta 1118,405-416 (1994).Google Scholar
- 10.M.D. Brand, Measurement of mitochondrial protonmotive force, in Bioenergetics: A Practical Approach, edited by G.C. Brown and C.E. Cooper (IRL Press, Oxford,1995).Google Scholar