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Electrophysiological abnormalities and enhanced reperfusion arrhythmias in the isolated hearts of hyperthyroid rats
Author(s) -
Miyazawa Katsuhiko,
Hashimoto Hisakuni,
Uematsu Toshihiko,
Nakashima Mitsuyoshi
Publication year - 1989
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1989.tb12566.x
Subject(s) - nadolol , electrophysiology , medicine , verapamil , euthyroid , cardiology , propranolol , prazosin , endocrinology , anesthesia , antagonist , thyroid , calcium , receptor
1 The influence of hyperthyroidism on electrophysiological characteristics and on reperfusion arrhythmias was examined in rat hearts. 2 Electrophysiological studies were performed with glass microelectrodes, and the experiments on reperfusion arrhythmias were done in isolated perfused hearts. 3 Ventricular muscle from hyperthyroid rats was more prone than that from euthyroid rats to develop triggered activity under conditions believed to cause myoplasmic Ca 2+ overload. 4 The severity of reperfusion arrhythmias was significantly enhanced in hyperthyroid preparations as compared with euthyroid ones. 5 The enhanced reperfusion arrhythmias in hyperthyroid rats were significantly reduced by propranolol (3 × 10 −7 m ), lignocaine (1 × 10 −5 m ) and verapamil (3 × 10 −8 m ), but not by nadolol (3 × 10 −7 m ) or prazosin (3 × 10 −7 m ). 6 These results suggest that increased heart rate due to hyperthyroidism and responses mediated via either α‐ or β‐adrenoceptors were not dominant causes of enhanced reperfusion arrhythmias in hyperthyroid hearts. 7 The increased tendency to develop triggered activity which was observed in the electrophysiological study, may be one possible explanation of enhanced reperfusion arrhythmias in hyperthyroid hearts.