To determine whether an altered modulation of transient outward K current (Ito) could affect ERP, the major isoforms of the rat alpha (Kv4.2, Kv4.3, Kv1.4) and beta (KChIP2) subunits were measured at mRNA level in the peri-infarcted and remote (left and right) ventricular myocardium of the MI+V and MI+GF rats, in comparison with SO+V. The gene discussed is KCNA4; the disease is myocardial infarction.