Role of mitochondria in control of calcium content of liver slices.

Abstract

INTRACELLULAR Ca2+ is thought to be important in the control of metabolic activity1,2. In liver cells, three energy-dependent transport activities capable of modifying the cellular distribution of this ion have been described—its accumulation by mitochondria3,4 and endoplasmic reticulum5 and its extrusion from the cell6,7. Mutual interactions, however, between these activities and their relative importance in determining total cell Ca2+ have so far been little studied in intact cells. One reason for this has been the difficulty of avoiding redistribution of Ca2+ between organelles when the cells are broken for isolation procedures, although Chen et al.8 used ruthenium red, added to the homogenisation medium, to prevent such redistribution in crab hepatopancreas. We now show that redistribution of Ca2+ into the mitochondria of rat liver can also be largely prevented by adding La3+ (another inhibitor of mitochondrial Ca2+ transport; ref. 9) to the homogenisation medium. We have also studied the contribution of mitochondria to the Ca2+ content of rat liver slices incubated in conditions in which total cell Ca2+ varies greatly.