Coenzyme Q(10) supplementation and recovery from ischemia in senescent ratmyocardium

Many studies have suggested that parenteral administration of coenzyme Q(10 ) (Q(10)) protects the myocardium of young experimental animals from post-i schemic reperfusion injury. Although parenteral administration, in contrast to per os supplementation, seems to elevate coenzyme Q concentrations in h eart tissue, it is not suitable for prophylactic use. In addition, the inci dence of ischemic events is greatest in older age. We studied the effect of Q(10) supplementation on myocardial postischemic recovery in 18-month-old Wistar rats. The treated group (n=9) received 10 mg/kg/day of Q(10) for 8 w eeks in their chow while the normal chow of the control group (n=9) contain ed less than 0.5 mg/kg/day of Q(10). The treatment clearly elevated plasma Q(10) concentration (286 +/- 25 mu mol/l and 48 +/- 30 mu mol/l, treated an d controls, respectively, p < 0.0001) but neither Q(9) nor Q(10) concentrat ions in heart tissue were affected by the supplementation. The isolated per fused hearts were subjected to 20 minutes of ischemia and 30 minutes of rep erfusion. The preischemic values of developed pressure (DP) but not contrac tility (+DP/Delta t) and relaxation (-DP/Delta t) were improved by Q(10) su pplementation (p = 0.034, p = 0.057 and p = 0.13, respectively) while in po stischemic recovery no differences were observed between the groups (p > 0. 05 at all time points). Also, in myocardial flow, myocardial oxygen consump tion (MVO2) and myocardial aerobic efficiency (DP/MVO2) the groups did not differ at any time points. Although dietary Q(10) supplementation clearly e levated plasma Q(10) concentrations in senescent rats, the coenzyme Q conte nts in heart tissue and myocardial recovery from ischemia were not affected . However, it is possible that the site of action for the reported benefici al effects of Q(10) is in the coronary endothelium rather than myocardium i tself.