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Cellular mechanism of pituitary adenylate cyclase‐activating polypeptide‐induced atrial tachyarrhythmia in canine isolated arterially perfused right atria
Author(s) -
Hirose Masamichi,
Chiba Shigetoshi
Publication year - 2003
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.2003.03940.x
Subject(s) - repolarization , medicine , endocrinology , atrial action potential , adenylate kinase , cyclase , fissipedia , carnivora , chemistry , electrophysiology , cardiology , stimulation , receptor
Summary 1. Pituitary adenylate cyclase‐activating polypeptide (PACAP) induces atrial tachyarrhythmia (AT). However, the cellular mechanism responsible for this remains unclear. 2. In six canine isolated arterially perfused right atria, high‐resolution optical mapping techniques were used to measure action potentials during control conditions and after PACAP injection (1 nmol). 3. During steady state pacing at a cycle length of 300 msec, the action potential duration was shorter during PACAP than during control ( P < 0.001). In addition, maximum repolarization gradients during PACAP (4 ± 1 msec/mm) were similar to those during control (5 ± 1 msec/mm; n = 6). Transmural repolarization gradients were also similar between the two groups. 4. After PACAP, AT was easily initiated with a single premature extrastimulus and was associated with a focal pattern of activation. However, AT was not initiated by a single premature stimulus during control. 5. In conclusion, the PACAP‐induced AT is associated with a focal pattern of activation that is independent of local repolarization gradients. These data suggest that increased dispersion of repolarization is not necessarily required for the induction of AT.