Biological and Pharmaceutical Bulletin
Online ISSN : 1347-5215
Print ISSN : 0918-6158
ISSN-L : 0918-6158
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Effects of Leonurine on L-Type Calcium Channel in Rat Ventricular Myocytes
Hong XinMing GuWen Wei WangShi Ying HuangFang Ping LiHui CaiYi Zhun ZhuXue Mei Zhang
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2012 Volume 35 Issue 8 Pages 1249-1256

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Abstract

Leonurine (Leo) is a special alkaloid principle of Herba leonuri that has recently been suggested to improve cardiovascular functions. To date, there is no direct ionic evidence of Leo on regulating calcium channels in the heart. In the present study, we examined the effects of Leo on action potentials and membrane currents recorded from isolated rat ventricular myocytes with the whole-cell patch clamp technique. Leo 100 µM shortened the action potential duration in a dose-dependent manner. Leo up to 200 µM had no significant effect on the Na+ current (INa) and K+ current (IK). However, Leo depressed the L-type Ca2+ current (ICa,L). In the presence of 20 and 100 µM Leo, the current density was decreased and the voltage at half maximal inactivation V0.5 shift to more negative potential. The recovery time constant was also delayed. In addition, the transcription and protein expression levels of L-type calcium channel (Cav1.2) in primary cultured neonatal myocytes from Sprague-Dawley rats were reduced by Leo treatment in a dose-dependent fashion as assessed by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot assays. We conclude that Leo inhibits L-type calcium channels in cardiomyocytes.

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© 2012 The Pharmaceutical Society of Japan
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