Is the preconditioning response conserved in senescent myocardium?

Background. Senescent myocardium differs from adult myocardium at both functional and cellular levels. To adjudicate the efficacy of ischemic preconditioning as an alternative or adjuvant myoprotective strategy a reproducible, age-independent, intact laboratory model is necessary. Methods. Adult (0.5 to 1.0 years) and senescent (5.7 to 8.0 years) sheep underwent 60 minutes of normothermic regional ischemia with 150 minutes of reperfusion. Group II (adult-ischemic preconditioning) and group IV (aged-ischemic preconditioning) underwent preconditioning with three 5-minute episodes of normothermic regional ischemia. Group I (adult-control) and group III (aged-control) were not preconditioned. Results. Risk size and infarct size weights were delineated by monastryl blue pigment infusion and buffered tetrazolium solution. Ischemic preconditioning was evidenced by an infarct size reduction of 54% for adult sheep and 47% for senescent sheep (p < 0.01 versus age-matched controls; p = not significant for adult versus senescent). Conclusions. The data suggest that the cellular pathways involved with the preconditioning response are well preserved in senescent myocardium and support the utility of the ovine heart model to investigate the clinical relevance of ischemic preconditioning for the increasingly aged population presently undergoing cardiac operations.