A protective effect of coenzyme Q10 on isolated rabbit ventricular muscle under hypoxic condition

Effects of coenzyme Q10 (CoQ10) on transmembrane action potential, isometric tension, and tissue ATP contents of isolated rabbit ventricular muscles were examined under the hypoxic condition and subsequent reoxygenation. CoQ10 (10 mg/kg/day) was administered intravenously to 15 rabbits for 3 days (CoQ10 group), and 15 other rabbits were treated only with a vehicle for CoQ10 (control group). Membrane action potentials, mechanical contraction, and ATP contents of the preparations under aerobic condition were not affected by the CoQ10 or vehicle pretreatment. Hypoxia for 60 min caused a shortening of action potential duration (APD), a decrease in peak developed tension (DT), and an elevation of resting tension (RT), as well as a decrease in ATP contents of the preparations in both groups. However, these changes were significantly less in the CoQ10 group than those in the control group. A better recovery of APD, DT, and RT of the preparations during reoxygenation period was also observed in the CoQ10 group. These results indicate that the prior and repetitive administration of CoQ10 may protect cardiac muscles from functional deterioration induced by hypoxia, suggesting a beneficial effect of this substance on the metabolism of the energy-depleted myocardium.