TY - JOUR T1 - <em>In Vitro</em> Electrocardiographic and Cardiac Ion Channel Effects of (-)-Epigallocatechin-3-Gallate, the Main Catechin of Green Tea JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther DO - 10.1124/jpet.110.169391 SP - jpet.110.169391 AU - Jiesheng Kang AU - Hsien Cheng AU - Junzhi Ji AU - Josephine Incardona AU - David Rampe Y1 - 2010/01/01 UR - http://jpet.aspetjournals.org/content/early/2010/05/18/jpet.110.169391.abstract N2 - Epigallocatechin-3-gallate (EGCG) is the major catechin found in green tea. EGCG is also available for consumption in the form of concentrated over-the-counter nutritional supplements. This compound is currently undergoing clinical trials for the treatment of a number of diseases including multiple sclerosis, and a variety of cancers. To date, little data exists regarding the effects of EGCG on the electrophysiology of the heart. Therefore, we examined the effects of EGCG on the electrocardiogram recorded from Langendorff-perfused guinea pig hearts, and on cardiac ion channels using patch clamp electrophysiology. EGCG had no significant effects on the electrocardiogram at concentrations of 3 and 10 μM. At 30 μM, EGCG prolonged PR and QRS intervals, slightly shortened the QT interval, and altered the shape of the ST-T-wave segment. The ST segment merged with the upstroke of the T-wave, and we noted a prolongation in the time from the peak of the T-wave until the end. Patch clamp studies identified the KvLQT1/minK K+ channel as a target for EGCG (IC50 = 30.1 μM). In addition, EGCG inhibited the cloned human cardiac Na+ channel Nav1.5 in a voltage-dependent fashion. The L-type Ca++ channel was inhibited by 20.8% at 30 μM while the K+ channels HERG and Kv4.3 were less sensitive to inhibition by EGCG. ECGC has a number of electrophysiological effects in the heart and these effects may have clinical significance when multi-gram doses of this compound are used in human clinical trials, or through self-ingestion of large amounts of over-the-counter products enriched in EGCG.The American Society for Pharmacology and Experimental Therapeutics ER -