Age-related changes in oxygen consumption and the SDH activity of liver homogenate of male garden lizards: effect of malonate and short-term cold stress.

The respiratory rate of liver homogenate in the male garden lizard showed a decline with advancing age. The mitochondrial marker enzyme, SDH of the liver, reached a peak activity in the middle-aged group and then declined. Malonate inhibition of the enzyme activity was greater in young and middle-aged groups of lizards than in old. Short-term cold stress (1 h at 0--4 degrees C) showed a differential age effect inducing a decline in enzyme activity of the middle-aged group and a rise in the old.