Blocking effect of 1389-S on the sodium current in isolated guinea-pig ventricular myocytes |
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| Authors: | I Hisatome S Matsuoka J Miyamoto M Sawaguchi H Omodani S Osaki H Kotake H Mashiba R Sato |
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| Institution: | 1st Department of Internal Medicine, Tottori University School of Medicine, Yonago, Japan. |
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| Abstract: | Under whole cell patch conditions, 1389-S blocked the INa in guinea-pig ventricular myocytes under steady state conditions (Kdrest = 30 microM, Kdi = 2.4 microM) with a shift of the inactivation curve to the hyperpolarizing direction. Both brief and long conditioning pulses could produce a use-dependent block of 1389-S. These results suggest that 1389-S had a higher affinity to the inactivated than to the rested state under steady state conditions and had a higher affinity to the activated state during train pulses as well as to the inactivated state, making channels unavailable for conduction upon activation. |
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