title: Apelin regulates the electrophysiological characteristics of atrial myocytes.
abstract: BACKGROUND
  Apelin, a potential agent for treating heart failure, has various ionic effects on ventricular myocytes. However, the effects of apelin on the atrium are not clear. The purpose of this study was to investigate the acute effects of apelin on the electrophysiological characteristics of atrial myocytes.
  
  
  METHODS
  Whole-cell patch-clamp techniques were used to investigate the action potential (AP) and ionic currents in isolated rabbit left atrial (LA) myocytes before and after the administration of apelin.
  
  
  RESULTS
  Apelin reduced LA AP duration measured at 90%, 50% and 20% repolarization of the amplitude by 11 ± 3%, 24 ± 5%, 30 ± 7% at 1 nM (n = 11), and by 14 ± 4%, 36 ± 6% and 45 ± 5% at 10 nM (n = 11), but not at 0·1 nM. Apeline (0·1, 1, 10 nM) did not change the amplitude, or resting membrane potential in LA myocytes. Apelin (1 nM) increased sodium currents, ultra-rapid potassium currents and the reverse mode of sodium-calcium exchanger currents, but decreased late sodium currents and L-type calcium currents and did not change transient outward currents or inward rectifier potassium currents in LA myocytes.
  
  
  CONCLUSIONS
  Apelin significantly changed the atrial electrophysiology with a shortening of AP duration, which may be caused by its effects on multiple ionic currents.
authors.affiliation: Division of Cardiology, Chi-Mei Medical Center, Tainan, Taiwan.
authors.forename: Chen-Chuan
authors.initials: CC
authors.lastname: Cheng
authors.forename: Punate
authors.initials: P
authors.lastname: Weerateerangkul
authors.forename: Yen-Yu
authors.initials: YY
authors.lastname: Lu
authors.forename: Yao-Chang
authors.initials: YC
authors.lastname: Chen
authors.forename: Yung-Kuo
authors.initials: YK
authors.lastname: Lin
authors.forename: Shih-Ann
authors.initials: SA
authors.lastname: Chen
authors.forename: Yi-Jen
authors.initials: YJ
authors.lastname: Chen
mesh_terms: D000200:Action Potentials / Q000187:drug effects*; D000818:Animals; D022062:Electrophysiologic Techniques, Cardiac / Q000379:methods; D006325:Heart Atria / Q000166:cytology*; D036341:Intercellular Signaling Peptides and Proteins / Q000494:pharmacology*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects*; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000502:physiology; D018408:Patch-Clamp Techniques; D011817:Rabbits
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; C495199:apelin-13 peptide