Action of Calcium on Corn Mitochondria

Abstract
No evidence for uncoupling of phosphorylation could be found unless concentrations of Ca were used which strongly suppressed respiration. Lower concentrations of Ca did lower P/O ratios, but this was due to diversion of phosphate from ATP formation into uptake. Ca did not stimulate ATPase or swelling rates. Contraction with ATP or succinate was enhanced by Ca, particularly in the presence of phosphate. Only small stimulations of acceptorless respiration were found; these were not sustained except in the presence of phosphate and ATP. In no respect did Ca act like 2,4-dinitrophenol. The action of Ca in diverting phosphate into uptake is discussed.