Table 1. Steady state parameters.
Oxygen uptake rate (Jo), Δψ and the ATP/ADP ratio were measured with mitochondria incubated in the presence of 4 mM succinate, 20 mM glucose, 100 μM ATP and, in the case of muscle 1.6 units·ml−1 hexokinase. The resultant steady state (labelled none) was perturbed by partial inhibition of the respiration module with 15 and 100 μM malonate for muscle and beta cell mitochondria respectively. In separate experiments, the same steady state was modulated by partial inhibition of the hexokinase module by lowering the amount of enzyme added to 0.018 unit·ml−1 (muscle) or by including 3.9 mM glucose 6-phosphate in the reaction medium (beta cells). The presented data are the mean±S.E.M. of n independent mitochondrial samples.
| Jo (nmol of O·min−1·mg−1) | Δψ (mV) | ATP/ADP ratio | ||||
|---|---|---|---|---|---|---|
| Inhibited module | Mean | n | Mean | n | Mean | n |
| Muscle | ||||||
| None* | 268±6.8 | 16 | 168±1.2 | 16 | 0.17±0.02 | 3 |
| Respiration | 189±5.7 | 11 | 157±0.9 | 11 | 0.15±0.02 | 3 |
| Hexokinase | 199±5.6 | 9 | 176±2.7 | 9 | 3.69±1.67 | 3 |
| Beta cells | ||||||
| None* | 65±2.2 | 15 | 132±2.3 | 15 | 0.55±0.14 | 6 |
| Respiration | 31±2.9 | 7 | 102±4.6 | 7 | 0.43±0.09 | 6 |
| Hexokinase | 42±1.2 | 3 | 134±2.4 | 3 | 1.27±0.75 | 3 |
* None represents steady state kinetics.