Development of transient outward current in neonatal rat ventricular myocytes during long-term primary culture

Abstract

Development of the transient outward current (I(sub to)) was investigated in cultured cardiac myocytes of neonatal rats. I(sub to) was compared at two different periods during the culture: one group at five days (n = 9) and another at 15 days (n = 10). For observations at 15 days, the current density of I(sub to) was tripled at to test voltage between -40 mV and +60 mV. As cultured myocytes matured, it was found that the steady-state inactivation curve of I(sub to) shifted to a depolarizing direction, while reversal potential shifted in a hyper-polarizing direction by about 20 mV. These results suggest that cultured neonatal rat ventricular myocytes can undergo the cell differentiation as observed by I(sub to) analysis.

標記一過性外向電流(Ito)の発生について研究した。培養中期間の異なる2つのグループすなわち5日齢グループと15日齢グループのItoを比較した。その結果、15日齢ではItoの電流密度は-40mVと+6mVの間のテスト電圧で3倍になった。培養した細胞が成熟するにつれて、Itoの定常状態不活性曲線が脱分極方向へシフトし、一方、約20mVで逆電流が過分極方向にシフトするのが観察された。これらの結果は、Ito解析により観察されたように、培養した新生児ラット心室筋細胞が細胞分化を行えることを示している。