Dynamics of Ca²⁺/calmodulin-dependent protein kinase II following acute myocardial ischemia—translocation and autophosphorylation

Authors: Uemura A.¹; Naito Y.²; Matsubara T.¹

Source: Biochemical and Biophysical Research Communications, Volume 297, Number 4, October 2002 , pp. 997-1002(6)

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Abstract:

Ca²⁺/calmodulin-dependent protein kinase (CaMK) family is responsive to changes in the intracellularCa²⁺ concentration. However, their functions have not been well established in the ischemia/reperfusion heart. The effects of myocardial ischemia on CaMKII, the most strongly expressed form, were investigated using isolated rat hearts. Rat hearts were rendered globally ischemic by stopping perfusion for 15 min, and then reperfused, heart ventricles being analyzed in each phase. Western blotting detected a decrease in the cytosolic and concomitant increase in the particulate fraction of CaMKII following transient ischemia. Redistribution to the cytosol was revealed on reperfusion. Northern blot showed CaMKII gene expression decreased by ischemia. Furthermore, autoradiography and confocal immunohistochemical findings provided autophosphorylation of CaMKII in the cytosol, ischemia causing decrease, with gradual recovery on reperfusion. These results indicate a transient partial translocation of CaMKII accompanied by kinase activity, with residual myocardial CaMKII undergoing autophosphorylation during ischemia and reperfusion, demonstrating two different characteristic dynamics of CaMKII.

Language: English

Document Type: Research article

DOI: http://dx.doi.org/10.1016/S0006-291X(02)02279-9

Affiliations: 1: Third Department of Internal Medicine, School of Medicine, Nagoya University, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan 2: Department of Pharmacology, Pharmaceutical Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan

Publication date: 2002-10-01