Effect of dipfluzine on sodium current in guinea-pig ventricular myocytes
10.3867/j.issn.1000-3002.2009.03.002
- VernacularTitle:双苯氟嗪对豚鼠心室肌细胞膜钠电流的影响
- Author:
Wei ZHANG
;
Qingfeng MIAO
;
Suwen SU
;
Jiayi CHENG
;
Yanting WANG
;
Yongjian ZHANG
- Publication Type:Journal Article
- Keywords:
dipfluzine;
heart ventricles;
myocytes,cardiac;
patch-clamp techniques;
sodium current
- From:
Chinese Journal of Pharmacology and Toxicology
2009;23(3):168-175
- CountryChina
- Language:Chinese
-
Abstract:
AIM To investigate effect of dipfluzine on sodium current (INa+) in isolated single guinea-pig ventricular myocytes. METHODS INa+ was measured by whole cell patch-clamp technique in single isolated guinea-pig ventricular myocytes which were prepared by enzymatic dissociation method. RESULTSCardiac INa+ was elicited by 50-ms pulses to +50 mV from holding potential at -80 mV with a step of +10 mV, which could be blocked completely by tetrodotoxin 10 μmol·L-1. The peak INa+ occurred at about -20 mV and the reversal potential for INa+ was about +30 mV. Dipfluzine inhibited cardiac INa+ in a concentration-dependent manner. The blocking effect of dipfluzine on INa+ was reversible. Dipfluzine suppressed cardiac INa+, without modifying maximum activation potential and reversal potential. The peak of INa+ was decreased by about 46% at -20 mV and shape of I-V curve was not altered by dipfluzine 40 μmol·L-1. Dipfluzine shifted the steady-state inactivation curve of INa+ towards more negative without changing the slope factor and produced very little change in the steady-state activation curve towards more positive. The mean half activation voltage was (-34.9±5.1) mV and slope factor was (6.0±4.8) mV under control condition and (-33.7±3.6) mV and (5.6±2.4) mV following exposure to dipfluzine 40 μmol·L-1. The half inactivation voltage was (-73.0±4.6)mV and slope factor was (4.8±1.8)mV under control condition and (-82.8±7.2)mV and (4.8±1.8)mV following dipfluzine 40 μmol·L-1 treatment. Dipfluzine delayed recovery of cardiac INa+ from inactivation state. The time course of recovery was (36±11) ms in control group and (79±28) ms in dipfluzine 40 μmol·L-1 group. CONCLUSION Dipfluzine inhi- bits cardiac INa+ in a concentration-dependent manner and has higher affinity for the inactivated state than that for resting state of Na+ channels.
