Table 1.

Oxidative phosphorylation in heart mitochondria of wild-type and sphk2^−/− mice

Parameter	Wild type	sphk2−/−
Glutamate and malate
State 3	251 ± 6	195 ± 18*
State 4	29 ± 3	19 ± 5
RCR	9.0 ± 0.7	13.5 ± 3.0
2 mM ADP	282 ± 6	211 ± 22*
DNP	291 ± 11	198 ± 23*
Succinate
State 3	355 ± 18	274 ± 18*
State 4	100 ± 7	84 ± 9
RCR	3.6 ± 0.1	3.3 ± 0.2
2 mM ADP	329 ± 18	253 ± 15*
DNP	309 ± 25	236 ± 16*
TMPD and ascorbate
2 mM ADP (azide sensitive)	897 ± 32	710 ± 49*

States 3 and 4 were measured in isolated heart mitochondria from wild-type (n=5) and sphk2^−/− mice (n=6) with glutamate and malate as substrates of respiratory complex I, succinate as substrate of respiratory complex II, and TMPD and ascorbate as substrates of respiratory complex IV. Data are expressed as nanoatoms of oxygen per minute per milligram of protein. Values are expressed as means ± se.

^*P < 0.05 vs. wild type.