Effects of calcium-channel blockers on picrotoxin-induced centrogenic arrhythmias in cats.
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概要
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Intravenous picrotoxin injection has been established as a model of producing arrhythmias, mainly through enhanced central sympathetic outflow. The effects of calcium-channel blockers, and a beta-blocker on these arrhythmias were tested in chloralose-anesthetized cats. Picrotoxin (10mg/kg, i.v.) produced mostly ventricular, sometimes supraventricular tachycardias and ectopic beats, as well as a marked elevation of arterial blood pressure. Nifedipine at the doses of 2μg/kg (i.v. or i.c.) and 5μg/kg (i.v.) transiently suppressed the arrhythmias in some of the cats tested. With the dose of 10μg/kg (i.v.), it promptly and consistently abolished the arrhythmias without recurrence and significantly reduced the blood pressure (-62±8/-59±8mmHg, Δsystolic pressure/Δdiastolic pressure, p<0.001, n=9). A similar degree of blood pressure reduction (-69±8/-67±7mmHg, n=6) after sodium nitroprusside (4-5mg/kg, i.v.) injection abolished the arrhythmias in 4 of 6 cats; however, there was marked ECG evidence of myocardial ischemia in 3 cats. Verapamil (50μg/kg, i.v.) transiently abolished the arrhythmias and significantly decreased the blood pressure (7/7 cats), whereas a larger dose (150μg/kg) had a persistent effect (2/4 cats). Propranolol at a dose of 240μg/kg also consistently abolished the arrhythmias without recurrence in all 4 cats.We conclude that nifedipine, verapamil and propranolol are effective in the treatment of picrotoxin-induced arrhythmias. This result indicates that calcium-channel blockers or beta-blockers may be clinically effective in the treatment or prevention of arrhythmias caused by intracranial lesions with enhanced sympathetic outflow.
- International Heart Journal刊行会の論文
著者
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Deng Jou-fang
Division Of Chinical Toxicology Department Of Medicine Veterans General Hospital
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CHIANG Benjamin
Division of Cardiology, Department of Internal Medicine, Veterans General Hospital and the National Yang Ming Medical College
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KUO Jon-Son
Division of Cardiology, Department of Medicine and the Department of Medical Research, Veterans General Hospital and Institute of Biomedical Sciences
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HOU Zone-Yuan
Division of Cardiology, Department of Medicine and the Department of Medical Research, Veterans General Hospital and Institute of Biomedical Sciences
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LIU Ren-Hon
Division of Cardiology, Department of Medicine and the Department of Medical Research, Veterans General Hospital and Institute of Biomedical Sciences
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CHAI Chok-Yung
Division of Cardiology, Department of Medicine and the Department of Medical Research, Academia Sinica
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DENG Jou-Fang
Division of Cardiology, Department of Medicine and the Department of Medical Research, Academia Sinica
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