Affiliations: Cardiac Surgical Research Unit, Baker Medical Research Institute, Prahran, Vic. 3181, Australia | Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic. 3168, Australia | Centre for Molecular Biology and Medicine, Melbourne, Australia
Abstract: The inferior recovery of cardiac function after interventional cardiac procedures in elderly patients compared to younger patients suggests that the aged myocardium is more sensitive to stress. We report two studies that demonstrate an age‐related deficit in myocardial performance after aerobic and ischemic stress and the capacity of CoQ_{10} treatment to correct age‐specific diminished recovery of function. In Study 1 the functional recovery of young (4 mo) and senescent (35 mo) isolated working rat hearts after aerobic stress produced by rapid electrical pacing was examined. After pacing, the senescent hearts, compared to young, showed reduced recovery of pre‐stress work performance. CoQ_{10} pretreatment (daily intraperitoneal injections of 4 mg/kg CoQ_{10} for 6 weeks) in senescent hearts improved their recovery to match that of young hearts. Study 2 tested whether the capacity of human atrial trabeculae (obtained during surgery) to recover contractile function, following ischemic stress in vitro (60 min), is decreased with age and whether this decrease can be reversed by CoQ_{10}. Trabeculae from older individuals (\geq 70 yr) showed reduced recovery of developed force after simulated ischemia compared to younger counterparts (<70 yr). Notably, this age‐associated effect was prevented in trabeculae pretreated in vitro (30 min at 24{}^\circC) with CoQ_{10} (400 \muM). We measured significantly lower CoQ_{10} content in trabeculae from \geq 70 yr patients. In vitro pretreatment raised trabecular CoQ_{10 } content to similar levels in all groups. We conclude that, compared to younger counterparts, the senescent myocardium of rats and humans has a reduced capacity to tolerate ischemic or aerobic stress and recover pre‐stress contractile performance, however, this reduction is attenuated by CoQ_{10} pretreatment.
Journal: Biofactors, vol. 9, no. 2-4, pp. 291-299, 1999
