Effects of diltiazem on the calcium accumulation and ATP synthesis simultaneously sustained by isolated rat heart mitochondria.

1. The effects of diltiazem have been investigated in isolated rat heart mitochondria exposed to conditions possibly attained in ischemia-damaged cells. 2. The results obtained indicate that diltiazem, at the concentrations expected within cells following pharmacological treatment, does not significantly affect the mitochondrial calcium content. 3. Diltiazem did not appear to modify ATP synthesis, and hence the capacity of mitochondria to sustain the ATP-requiring processes needed for the recovery of cardiac cells.