title: Increased intracellular calcium concentration causes electrical turbulence in guinea pig ventricular myocytes.
abstract: Dysregulation of intracellular Ca(2+) homeostasis is associated with various pathological conditions and arrhythmogenesis of the heart. The objective of this study was to investigate the effects of an acute increase in intracellular Ca(2+) concentration ([Ca(2+)](i)) on the electrophysiology of ventricular myocytes by mimicking intracellular Ca(2+) overload. The [Ca(2+)](i) was clamped to either a controlled (65-100 nmol L(-1)) or increased (1 μmol L(-1)) level. The transmembrane action potentials and ionic currents were recorded using whole-cell patch clamp techniques. We found that the acute increase in [Ca(2+)](i) shortened the action potential duration, reduced the action potential amplitude, maximum depolarization velocity and resting membrane potential, caused delayed after-depolarizations (DADs), and triggered activity-compared with these parameters in the control. The increased [Ca(2+)](i) augmented late I (Na) in a time-dependent manner, reduced I (CaL) and I (K1), and increased I (Kr) but not I (Ks). The results of this study can be used to explain calcium overload-induced ventricular arrhythmias.
authors.affiliation: Cardio-Electrophysiological Research Laboratory, Medical College of Wuhan University of Science and Technology, Wuhan 430081, China.
authors.forename: Xinrong
authors.initials: X
authors.lastname: Fan
authors.forename: Jihua
authors.initials: J
authors.lastname: Ma
authors.forename: Wei
authors.initials: W
authors.lastname: Wan
authors.forename: Peihua
authors.initials: P
authors.lastname: Zhang
authors.forename: Chao
authors.initials: C
authors.lastname: Wang
authors.forename: Lin
authors.initials: L
authors.lastname: Wu
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D006168:Guinea Pigs; D006352:Heart Ventricles / Q000166:cytology*; D006801:Humans; D007477:Ions / Q000378:metabolism; D008564:Membrane Potentials / Q000502:physiology; D032383:Myocytes, Cardiac / Q000502:physiology*; D018408:Patch-Clamp Techniques; D011897:Random Allocation
chemical_list: D007477:Ions; D002118:Calcium