Table 5. Mitochondrial ATP production rates standardized with citrate synthase activity.

genotype	Substrate combination (units/unit CS)
	G+M	G+S	PC+M	P+M	S	S+R
TK2+/+	1.94±0.83	3.81±2.28	1.38±0.54	3.38±1.79	3.63±2.48	1.53±0.2
TK2−/−	1.69±1.03	2.86±1.50	1.13±0.51	2.27±1.31	1.87±1.54	1.38±1.25

CS: citrate synthase; G: glutamate; M: malate; S: succinate; P: pyruvate; PC: palmitoyl-L-carnitine; R: rotenone. Mitochondrial CS activity was similar in the genotypes. For each time point data from 14 days old mice, three from each genotype, have been used (n = 3) and are presented as mean ± SEM. Statistical comparisons (two-tailed unpaired Student’s t-test) between TK2^+/+ and TK2^−/− were made but no statistical differences were detected.