© 1996 by European Society of Cardiology
Copyright © 1996, European Society of Cardiology
Glibenclamide attenuates peaked T wave in early phase of myocardial ischemia
First Department of Internal Medicine, Yamagata University School of Medicine, 2-2-2 Iida-Nishi, Yamagata 990-23, Japan
* Corresponding author. Fax (+ 81-236) 28-5305; Tel. (+ 81-236) 28-5302.
Objectives: ECG peaked T wave appears during the early phase of myocardial ischemia, but the underlying mechanisms remain unknown. The purpose of this study was to elucidate the role of ATP-sensitive K+ channel (KATP) in this ECG change.
Methods: In 12 anesthetized, open-chest dogs, the sinus node was crushed and the right atrium was paced at a cycle length of 400 ms. The left anterior descending coronary artery was abruptly occluded for 60 s before (control) and 15 min after an intravenous infusion of vehicle (n = 6) or glibenclamide (1 mg/kg, n = 6), a blocker of KATP. Forty-eight epicardial electrograms were simultaneously recorded from the anterior surface of the left ventricle. The potentials at 40, 80 and 120 ms from the J point were measured, and these points corresponded to the early, middle and late phases of the T wave, respectively.
Results: During the control occlusion, T wave increased time-dependently and the maximal T-wave change was noted at the end of 60 s of coronary occlusion. The extents of T-wave elevation at the early, mid and late T phases were 5.5 ± 0.5, 7.3 ± 0.8 and 11.7 ± 1.8 mV, respectively, and these T-wave elevations were significantly reduced by 33 ± 21%, 59 ± 12% and 63 ± 13%, respectively, after the pretreatment with glibenclamide but not with its vehicle. The % reductions of mid and late T by glibenclamide were significantly larger than that of early T wave (P < 0.05).
Conclusions: An abrupt coronary occlusion accompanied peaked T wave as an early ECG wave change. As the extent of this T-wave elevation was attenuated by glibenclamide, the ischemia-induced alteration of ventricular repolarization can partly (60%) be explained by the modification of KATP activation.
KEYWORDS Potassium channnel; ATP sensitive; Sulphonylureas; Myocardial ischemia; ECG
1 Please also see Editorial, Cardiovasc Res 1996;31:688-690.
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