title: Tea polyphenols promote cardiac function and energy metabolism in ex vivo rat heart with ischemic/reperfusion injury and inhibit calcium inward current in cultured rat cardiac myocytes.
abstract: OBJECTIVE
  To investigate the protective effects of tea polyphenols (TP) against myocardial ischemia/reperfusion (IR) injuries and explore the possible mechanisms.
  
  
  METHODS
  Langendorff-perfused rat hearts were subjected to ischemia for 30 min followed by reperfusion for another 30 min. Myocardial function indices were measured by a left ventricular cannula via a pressure transducer connected to the polygraph in isolated Langendorff hearts and energy metabolism was measured using (31)P nuclear magnetic resonance (NMR) spectroscopy. Whole-cell atch-clamp technique was used to record calcium inward current (I(Ca-L)) in cultured rat cardiac myocytes.
  
  
  RESULTS
  Compared with the control hearts, the ex vivo rat hearts with 2.5 mg/L TP treatment showed significantly increased left ventricular developed pressure (LVDP), maximal rise rate of LVDP (+dp/d(tmax)), maximal fall rate of LVDP (-dp/dt(max)), and coronary flow (CF) (P<0.05). During both cardiac ischemia and reperfusion phase, ATP and PCr levels were elevated significantly in TP-treated hearts compared with those in the control hearts (P<0.05). In cultured rat cardiac myocytes, ICa-L was remarkably decreased by TP at the doses of 2.5 and 5.0 mg/L (P<0.01).
  
  
  CONCLUSIONS
  Our results support a possible protective role of TP against myocardial IR injury by improving myocardial energy metabolism and inhibiting I(Ca-L) in the cardiac myocytes.
authors.affiliation: State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, Beijing 100039, China.E-mail: 13522700930@139.com.
authors.forename: Hua-Jin
authors.initials: HJ
authors.lastname: Dong
authors.forename: Jie
authors.initials: J
authors.lastname: Li
authors.forename: Hao
authors.initials: H
authors.lastname: Zhan
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.forename: Rui-Bin
authors.initials: RB
authors.lastname: Su
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D002478:Cells, Cultured; D004734:Energy Metabolism; D006321:Heart / Q000187:drug effects; D066298:In Vitro Techniques; D015428:Myocardial Reperfusion Injury; D009206:Myocardium / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism; D059808:Polyphenols / Q000494:pharmacology*; D051381:Rats; D013662:Tea / Q000737:chemistry
chemical_list: D015220:Calcium Channels; D059808:Polyphenols; D013662:Tea; D002118:Calcium