Src family kinase and adenosine differentially regulate multiple MAP kinases in ischemic myocardium: Modulation of MAP kinases activation by ischernic preconditioning

Recent studies suggest that ischemia activates Src and members of the mitog en-activated protein (MAP) kinase superfamily and their downstream effector s, including big MAP kinase 1 (BMK1) and p90 ribosomal S6 kinase (p90RSK). It has also been reported that adenosine is released during ischemia and in volved in triggering the protective mechanism of ischemic preconditioning. To assess the roles of Src and adenosine in ischemia-induced MAP kinases ac tivation, we utilized the Src inhibitor PP2 (4-Amino-5-(4-chlorophenyl)-7-( t-butyl)pyrazolo[3,4-d]pyrimidine) and the adenosine receptor antagonist 8- (p-sulfophenyl) theophylline (SPT) in perfused guinea pig hearts. PP2 (1 mu m) inhibited ischemia-induced Src, BMK1 and JNK activation but not JAK2 and p38 activation. SPT inhibited ischemia-mediated p38 and JNK activation. Th ese results demonstrate that Sro family kinase and adenosine regulate MAP k inases by parallel pathways. Preconditioning significantly improved both re covery of developed pressure and dp/dt in isolated guinea pig hearts. Since the protective effect of preconditioning was blocked by PP2 (1 muM) and SP T (50 muM), we next investigated the regulation of Src, MAP kinases and p90 RSK during preconditioning. The activity and time course of ERK1/2 was not changed, but p90RSK activation by reperfusion was completely inhibited by p reconditioning. In contrast, the activation by ischemia of Src, BMK1, p38 a nd JNK was significantly faster in preconditioned hearts. Maximal BMK1 acti vation by ischemia was also significantly enhanced by preconditioning. These data suggest important roles for Src family kinases and adenosine in mediating preconditioning, and suggest specific roles for individual MAP ki nases in preconditioning. (C) 2001 Academic Press.