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[Alterations of cardiac hemodynamics, sodium current and L-type calcium current in rats with L-thyroxine-induced cardiomyopathy.] [Ariticle in Chinese]

Wang Jing, ZHANG Wei-Dong, LIN Mu-Sen, ZHAI Qing-Bo, YU Feng^*

Department of Clinical Pharmacy, China Pharmaceutical University, Nanjing 210009, China

Abstract

The aim of the present study is to investigate the alterations of cardiac hemodynamics, sodium current (INa) and L-typecalcium current (ICa-L) in the cardiomyopathic model of rats. The model of cardiomyopathy was established by intraperitoneal injectionof L-thyroxine (0.5 mg/kg) for 10 d. The hemodynamics was measured with biological experimental system, and then INa and ICa-Lwererecorded by using whole cell patch clamp technique. The results showed that left ventricular systolic pressure (LVSP), left ventriculardeveloped pressure (LVDP), ±dp/dtmax in cardiomyopathic group were significantly lower than those in the control group, while leftventricular end-diastolic pressure (LVEDP) in cardiomyopathic group was higher than that in the control group. Intraperitonealinjection of L-thyroxine significantly increased the current density of INa [(-26.2±3.2) pA/pF vs (-21.1±6.3) pA/pF, P<0.01], shiftedsteady-state activation and inactivation curves negatively, and markedly prolonged the time constant of recovery from inactivation. Onthe other hand, the injection of L-thyroxine significantly increased the current density of ICa-L [(-7.9±0.8) pA/pF vs (-5.4±0.6) pA/pF,P<0.01)], shifted steady-state activation and inactivation curves negatively, and obviously shortened the time constant of recoveryfrom inactivation. In conclusion, the cardiac performance of cardiomyopathic rats is similar to that of rats with heart failure, in whichthe current density of INa and especially the ICa-L are enhanced, suggesting that calcium channel blockade and a decrease in Na+ permeabilityof membrane may play an important role in the treatment of cardiomyopathy.

Key words: L-thyroxine; cardiomyopathy; hemodynamics; INa; ICa-L; patch clamp

Received: 2010-04-29　　Accepted: 2010-07-13

Corresponding author: 于锋　　E-mail: yufengcpu@163.com

Citing This Article：

Wang Jing, ZHANG Wei-Dong, LIN Mu-Sen, ZHAI Qing-Bo, YU Feng. [Alterations of cardiac hemodynamics, sodium current and L-type calcium current in rats with L-thyroxine-induced cardiomyopathy.] [Ariticle in Chinese] . Acta Physiol Sin 2010; 62 (4): 325-332 (in Chinese with English abstract).