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 ischemi c 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) s heep underwent 60 minutes of normothermic regional ischemia with 150 m inutes of reperfusion. Group II (adult-ischemic preconditioning) and g roup IV (aged-ischemic preconditioning) underwent preconditioning with three 5-minute episodes of normothermic regional ischemia. Group I(ad ult-control) and group III (aged-control) were not preconditioned. Res ults. Risk size and infarct size weights were delineated by monastryl blue pigment infusion and buffered tetrazolium solution. Ischemic prec onditioning was evidenced by an infarct size reduction of 54% for adul t sheep and 47% for senescent sheep (p < 0.01 versus age-matched contr ols; p = not significant for adult versus senescent). Conclusions. The data suggest that the cellular pathways involved with the preconditio ning response are well preserved in senescent myocardium and support t he utility of the ovine heart model to investigate the clinical releva nce of ischemic preconditioning for the increasingly aged population p resently undergoing cardiac operations.