Open AccessRole of Acetylcholine in Electrical Stimulation-Induced Arrhythmia in Rat Isolated Atria
Author(s) -
Carlos Godoy,
Rosana A. Bassani,
José Wilson Magalhães Bassani
Publication year - 1999
Publication title -
journal of cardiovascular pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.762
H-Index - 100
eISSN - 1533-4023
pISSN - 0160-2446
DOI - 10.1097/00005344-199910000-00001
Subject(s) - stimulation , atropine , acetylcholine , medicine , atrium (architecture) , atrial flutter , cardiology , electrophysiology , anesthesia , chemistry , atrial fibrillation
In this study, we used the spontaneously beating, isolated rat right atrium as an in vitro model to study arrhythmogenic effects of electrical stimulation. A tetrapolar platinum electrode was used for stimulation and recording of atrial electrical activity at 36.5 degrees C (spontaneous rate, 4.9+/-0.3 Hz). A flutter-like pattern of arrhythmia was reproducibly induced by application of stimulus trains (250 pulses, 66.7 Hz). Arrhythmia was characterized by regular and very short cycle length (40-70 ms), each episode lasting from 3 s to >5 min. In control conditions, application of one to five pulse trains was sufficient to induce arrhythmia. However, atropine (but not propranolol) completely blocked arrhythmia induction (10-15 consecutive trains were ineffective). The ability of electrical stimulation to evoke arrhythmia was restored after atropine washout. A milder stimulation protocol (30 pulses, 50 Hz), which was unable to evoke arrhythmia in control conditions, was fully effective in the presence of 1 microM acetylcholine (ACh). Furthermore, a similar flutter-like pattern could be induced in isolated left atria in the presence of ACh. Our results point out an arrhythmogenic effect of neurally released ACh in the isolated right atrium on atrial electrical stimulation.