Effect of temperature on calcium exchange in digitonin-treated rat ventricular myocytes.

The effect of a change in temperature on net mitochondrial Ca2+ exchange has been investigated in a suspension of adult rat ventricular myocytes. Temperature was varied between 42 degrees C and 15 degrees C. Hypothermia reduced the initial rate of respiration-dependent Ca2+ uptake and reduced the Na+-sensitivity of Ca2+ efflux. The net result of these alterations is that at low temperatures, the Ca2+ level at which a steady-state between mitochondria and sarcoplasm is maintained, will be raised.