Altered expression and activation of mitogen-activated protein kinases in diabetic heart during cardioplegic arrest and cardiopulmonary bypass

Background. We investigated whether mitogen-activated protein kinases (MAPKs) are changed in the hearts of patients with diabetes after cardioplegia and cardiopulmonary bypass (CP/CPB) operations. Methods. Biopsies from the right atrial appendage were harvested pre- and post-CP/CPB from nondiabetic (ND) patients (n = 8, hemoglobin A1c (HbA1c) = 5.4 +/- 0.12); patients with controlled diabetes (CDM) (n = 8, HbA1c = 6.5 +/- 0.15); and patients with uncontrolled diabetes (UDM) (n = 8, HbA1c = 9.6 +/- 0.3) undergoing coronary artery bypass grafting. The expression and/or activation of the p38-MAPK, ERK1/2, INK, and MKP-1 in the right-atrial tissues were analyzed by Western blotting. The vasomotor function of coronary arterioles was measured by videomicroscopy. Results. The post-CP/CPB levels of total p38-MAPK were decreased in the 3 groups as compared with their pre-CP/CPB levels (P<.05). There were increases in phospho-p38-MAPK, phospho-ERK1/2, and MKP-1 in UDM patients as compared with ND and CDM patients at baseline (P<.05). Compared to pre-CP/CPB, the post-CP/CPB levels of phospho-p38-MAPK decreased in the UDM group but were unaltered in the ND and CDM groups; however, the post-CP/CPB levels of phospho-p38-MAPK still remained greater than the post-CP/CPB levels of the other 2 groups. Post-CP/CPB levels of phospho-ERK1/2 were increased in the ND and CDM groups but were decreased in the UDM group compared to their pre-CP/CPB levels, respectively (P<.05). There were no significant differences in phospho-JNK in 3 groups at baseline. Post-CP/CPB levels of phospho-JNK, however, were increased in the 3 groups and were more pronounced in the myocardium of the UDM group (P<.05). After CP/CPB, the protein levels of MKP-1 were unchanged in the 3 groups when compared with their pre-CP/CPB levels. Post-CP/CPB levels of MKP-1, however, remained greater in the UDM group than in the ND and CDM groups. The post-CP/CPB contractile responses to the thromboxane A2 analog U46619 were significantly impaired in all 3 groups compared with pre-CP/CPB contractile responses. These impairments were more pronounced in the UDM group. Conclusion. Uncontrolled diabetes is associated with changes in expression of and activation of MAPKs and vasomotor dysfunction in the setting of CP/CPB.