Electriophysiological properties of arrhythmogenic action of endothelin in guinea pig papillary muscles
Abstract：Objective: Present study focuses on the electrophysiologieal properties of arrhythunogenic action of endothelin and itsunderlying mechanisms. Methods: Transmembrane action potential (AP) in guinea pig papillary muscles were recorded withmicroelectrode and the parmeters of APs were analysed with computer. Results: ET1 significantly prolonged APD in concen-tration-dependent manner and induced stable EADs at lower concentration of [ Mg2 + ]0. The occurence of EADs induced by ET1, their amplitudes and triggered burst duration (TBD) were markdly dependent on the dose and the drive cycle length. Boththe prolongation APD and occurence of EADs evoked by ET-1 were abolished by either BQ-123,an ETA receptor selective antagonist,or Nif, a Ca2+ channel blocker. Conelusion: EADs induced by ET-1 in the papillary muscles might be attributed tointracellular Ca2+ overloading as result of an activation of Ca2+ channel via ETA receptor. ET-iduced abnormalities of reploarization, as were manifested by EADs, provided an important electrophysiological basis for the occurence of fatal arrhythmia.
Keywords：endothelinearly afterdepolarizationarrhythmia
Publication Date：2000-01-01
Online Publishing Date：2026-09-12(First online date of this platform, not the publication date of the document)
Pages：5( 112-116 )