Region-specific mechanisms of corticosteroid-mediated inotropy in rat cardiomyocytes.

Regional differences in ion channel activity in the heart control the sequence of repolarization and may contribute to differences in contraction. Corticosteroids such as aldosterone or corticosterone increase the L-type Ca current (I) in the heart via the mineralocorticoid receptor (MR). Here, we investigate the differential impact of corticosteroid-mediated increase in I on action potentials (AP), ion currents, intracellular Ca handling and contractility in endo- and epicardial myocytes of the rat left ventricle.