Biological significance of enhanced mitochondrial membrane potential in regenerating liver

Liver mitochondrial membrane potential was assessed during regeneration following partial hepatectomy in rabbits. Absorbance change of safranine O per milligram of mitochondrial protein was used to evaluate mitochondrial membrane potential. Absorbance change was calibrated to the membrane potential in millivolts produced by valinomycin-induced potassium diffusion potential. At 24 hr after hepatectomy, absorbance change of safranine O per milligram of mitochondrial protein increased from 15.0 +/- 2.2 X 10(-3) to 37.4 +/- 3.3 X 10(-3) per mg (p less than 0.005). This represents a mitochondrial membrane potential increase from 77.0 +/- 4.6 to 124.4 +/- 6.7 mV. Phosphorylative activity increased from 59.9 +/- 5.0 to 106.1 +/- 7.4 nmoles ATP synthesized per mg per min (p less than 0.005). The enhancement of phosphorylative activity was closely linked to the elevation in liver mitochondrial membrane potential (r = 0.77, p less than 0.005). We suggest that elevation of mitochondrial membrane potential, coupled with enhanced oxidative and phosphorylative activities, plays an important role in the regeneration process following hepatectomy.