title: [Effect of tetradrine on electrophysilogic changes caused by rising of left ventricular preload in guinea pigs].
abstract: OBJECTIVE
  To investigate the changes of guinea pig heart electrophysiological properties caused by increasing left ventricular preload, and to assess the effects of tetradrine on these changes.
  
  
  METHODS
  Working model preparation of guinea pig hearts in vitro was used, and the preload of left ventricle was increased by adjusting the prefusion pressure of left atria. The changes of heart electrophysiologic parameters including monophasic action potential duration (MAPD90), monophasic action potential amplitude (MAPA), effective refractory period (ERP) and ventricular fibrillation threshold (VFT) were observed before and after altering the preload of left ventricle, and compared in the absence and presence of tetradrine, streptomycin or verapamil.
  
  
  RESULTS
  The rising of left ventricular preload led to shortening of MAPD90, ERP, and to descent of MAPA, VFT (all P<0.01). Both Tetradrine and streptomycin inhibited these changes of heart electrophysiologic parameters caused by elevation of left ventricular afterload (all P<0.01). In contrast, verapamil had no effects on the preload-related electrophysiological changes (all P>0.05).
  
  
  CONCLUSIONS
  Electrophysiologic changes caused by increasing left ventricular preload may be inhibited by tetrandrine, through inhibition of stretch-activated ion channels.
authors.affiliation: Cardiovascular Disease Department, First Hospital Affiliated to Medical College of Zhejiang University, Hangzhou 310003, Zhejiang, China. wangxx19730312@yahoo.com.cn
authors.forename: Xing-xiang
authors.initials: XX
authors.lastname: Wang
authors.forename: Jun-zhu
authors.initials: JZ
authors.lastname: Chen
authors.forename: Long-xian
authors.initials: LX
authors.lastname: Cheng
authors.forename: Li-Long
authors.initials: LL
authors.lastname: Zhou
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000470:Alkaloids / Q000302:isolation & purification / Q000494:pharmacology*; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000302:isolation & purification / Q000494:pharmacology*; D044182:Benzylisoquinolines / Q000302:isolation & purification / Q000494:pharmacology*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D004365:Drugs, Chinese Herbal / Q000302:isolation & purification / Q000494:pharmacology; D005260:Female; D006168:Guinea Pigs; D006321:Heart / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D010946:Plants, Medicinal / Q000737:chemistry; D012032:Refractory Period, Electrophysiological / Q000187:drug effects*; D031609:Stephania tetrandra / Q000737:chemistry; D013307:Streptomycin / Q000494:pharmacology; D016277:Ventricular Function, Left / Q000187:drug effects*; D014700:Verapamil / Q000494:pharmacology
chemical_list: D000470:Alkaloids; D000889:Anti-Arrhythmia Agents; D044182:Benzylisoquinolines; D002121:Calcium Channel Blockers; D004365:Drugs, Chinese Herbal; C009438:tetrandrine; D014700:Verapamil; D013307:Streptomycin