title: Electrolyte disturbances differentially regulate sinoatrial node and pulmonary vein electrical activity: A contribution to hypokalemia- or hyponatremia-induced atrial fibrillation.
abstract: BACKGROUND
  Hypokalemia and hyponatremia increase the occurrence of atrial fibrillation. Sinoatrial nodes (SANs) and pulmonary veins (PVs) play a critical role in the pathophysiology of atrial fibrillation.
  
  
  OBJECTIVE
  The purpose of this study was to evaluate whether electrolyte disturbances with low concentrations of potassium ([K(+)]) or sodium ([Na(+)]) modulate SAN and PV electrical activity and arrhythmogenesis, and to investigate potential underlying mechanisms.
  
  
  METHODS
  Conventional microelectrodes were used to record electrical activity in rabbit SAN and PV tissue preparations before and after perfusion with different low [K(+)] or [Na(+)], interacting with the Na(+)-Ca(2+) exchanger inhibitor KB-R7943 (10 μΜ).
  
  
  RESULTS
  Low [K(+)] (3.5, 3, 2.5, and 2 mM) decreased beating rates in PV cardiomyocytes with genesis of delayed afterdepolarizations (DADs), burst firing, and increased diastolic tension. Low [K(+)] (3.5, 3, 2.5, and 2 mM) also decreased SAN beating rates, with genesis of DADs. Low [Na(+)] increased PV diastolic tension, DADs, and burst firing, which was attenuated in the co-superfusion with low [K(+)] (2 mM). In contrast, low [Na(+)] had little effect on SAN electrical activities. KB-R7943 (10 μΜ) reduced the occurrences of low [K(+)] (2 mM)- or low [Na(+)] (110 mM)-induced DAD and burst firing in both PVs and SANs.
  
  
  CONCLUSIONS
  Low [K(+)] and low [Na(+)] differentially modulate SAN and PV electrical properties. Low [K(+)]- or low [Na(+)]-induced slowing of SAN beating rate and genesis of PV burst firing may contribute to the high occurrence of atrial fibrillation during hypokalemia or hyponatremia.
authors.affiliation: Division of Cardiology, Sijhih Cathay General Hospital, New Taipei City, Taiwan; School of Medicine, Fu-Jen Catholic University, New Taipei City, Taiwan.
authors.forename: Yen-Yu
authors.initials: YY
authors.lastname: Lu
authors.affiliation: Division of Cardiology, Chi-Mei Medical Center, Tainan, Taiwan.
authors.forename: Chen-Chuan
authors.initials: CC
authors.lastname: Cheng
authors.affiliation: Department of Biomedical Engineering, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Yao-Chang
authors.initials: YC
authors.lastname: Chen
authors.affiliation: Division of Cardiovascular Medicine, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan; Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Yung-Kuo
authors.initials: YK
authors.lastname: Lin
authors.affiliation: National Yang-Ming University, School of Medicine; Division of Cardiology and Cardiovascular Research Center, Veterans General Hospital-Taipei, Taipei, Taiwan.
authors.forename: Shih-Ann
authors.initials: SA
authors.lastname: Chen
authors.affiliation: Division of Cardiovascular Medicine, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan; Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan. Electronic address: yjchen@tmu.edu.tw.
authors.forename: Yi-Jen
authors.initials: YJ
authors.lastname: Chen
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D001281:Atrial Fibrillation / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology*; D004195:Disease Models, Animal; D004573:Electrolytes / Q000378:metabolism*; D007008:Hypokalemia / Q000150:complications*; D007010:Hyponatremia / Q000150:complications*; D008297:Male; D008839:Microelectrodes; D032383:Myocytes, Cardiac / Q000378:metabolism / Q000473:pathology; D011667:Pulmonary Veins / Q000378:metabolism* / Q000503:physiopathology; D011817:Rabbits; D012849:Sinoatrial Node / Q000378:metabolism / Q000503:physiopathology*; D019831:Sodium-Calcium Exchanger
chemical_list: D004573:Electrolytes; D019831:Sodium-Calcium Exchanger
keywords: Atrial fibrillation; Hypokalemia; Hyponatremia; Pulmonary vein; Sinoatrial node