A possible role of HSP70 in mediating cardioprotection in patients undergoing CABG.

Heat shock protein 70 (HSP70) has been reported to be involved in myocardial self-preservation system. This study shows direct evidence of the effect of HSP70 on lymphocytes during ischemia and reperfusion in CABG (coronary artery bypass graft) surgery. Lymphocytes were separated from the blood obtained from 10 patients undergoing CABG at different time intervals. (i) Baseline samples (drawn before onset of bypass), (ii) ischemic samples (30 min after cross-clamp) and (iii) reperfusion samples (10 min after the cross clamp removal) were incubated with recombinant HSP70 and the cells were harvested after 36 h. The effect of HSP70 was monitored by measuring second messengers such as intracellular calcium, protein kinase C (PKC) and inositol triphosphate (IP3). In addition CD69 expression was also measured. The results showed a significant decrease in intracellular calcium and CD69 expression in ischemia and further in reperfusion samples as compared to their respective untriggered controls. PKC and IP3 levels however remained unaffected. The protective effect of HSP70 during ischemia and reperfusion could thus be attributed to decreasing intracellular calcium and CD69 expression. This study could therefore provide a mechanism of cardioprotection afforded by HSP70.