Effect of imidapril on heterogeneity of slow component of delayed rectifying K+ current in rabbit left ventricular hypertrophic myocytes.

AIM To investigate the transmural heterogeneous change of slow component of delayed rectifying potassium current in rabbit left ventricular hypertrophic myocytes and the effect of long-term treatment with imidapril (Imi). METHODS Rabbits were divided into hypertrophy group (left ventricular hypertrophy induced by partial ligation of abdominal aorta), Imi-treated group (surgical treatment as hypertrophy group was treated with Imi), and Sham-operated group as control. Whole-cell patch-clamp technique was used to record potassium currents. RESULTS (1) Membrane capacitance was larger in hypertrophic cells than in sham-operated and Imi-treated cells. Action potential durations (APD) of epicardium (Epi), midmyocardium (M), and endocardium (Endo) were remarkably longer in hypertrophic cells than those in Imi-treated and sham-operated cells. The prolongation of APD90 of M was the most pronounced in three layer myocytes of hypertrophic group. (2) The densities of I(Ks,tail) of hypertrophic cells were reduced by Epi 25.3 %+/-2.9 %, M 38.0 %+/-3.7 % and Endo 20.3 %+/-4.7 % compared with those of sham-operated cells. The decrease of IKs,tail density was more pronounced in M than in Epi and Endo (n = 13, P<0.01 vs Epi or Endo). (3) The density of I(Kr,tail) in Imi-treated cells was not different from that in sham-operated cells significantly (n=10). CONCLUSION Imi reduced prolongation of APD and inhibited the heterogeneous change of I(Ks,tail) in rabbit left ventricular hypertrophic myocytes.