Premium
EFFECTS OF CALCIUM ANTAGONISTS ON THE ALTERNATION OF THE ST‐T COMPLEX AND ASSOCIATED CONDUCTION ABNORMALITIES DURING CORONARY OCCLUSION IN DOGS
Author(s) -
HASHIMOTO HISAKUNI,
NAKASHIMA MITSUYOSHI
Publication year - 1981
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.1476-5381.1981.tb09981.x
Subject(s) - diltiazem , verapamil , cardiology , medicine , st segment , st depression , coronary occlusion , electrical conduction system of the heart , effective refractory period , st elevation , refractory period , electrocardiography , anesthesia , occlusion , myocardial infarction , calcium
1 The effects of Ca 2+ ‐antagonists on the relationships between alternate changes in the ST‐T complex in the epicardial electrogram, ST‐T alternans, and associated excitation‐conduction abnormalities during coronary occlusion were examined in anaesthetized dogs 2 Epicardial unipolar electrograms, bipolar electrograms (BPEG) and monophasic action potentials (MAP) were recorded with unipolar, composite and suction electrodes, respectively 3 ST‐T alternans was associated with serious conduction delay. During the period of ST‐T alternans, the amplitude of MAP changed alternately and the negative deflection of the ST‐T complex was associated with a larger MAP. A depression of the TQ level and decrease in the resting potential of MAP were marked 4 Verapamil (0.2 mg/kg) and diltiazem (0.5 mg/kg) inhibited ST‐T alternans, conduction abnormalities, TQ depression and changes in MAP. However, after these drugs, the TQ depression and the decrease in the resting potential were evident after a longer period of occlusion at a time when ST‐T alternans, conduction abnormalities and alternate changes in MAP were still inhibited. Dipyridamole (0.5 mg/kg) had no effect on either ST‐T alternans or the conduction abnormalities 5 Verapamil and diltiazem inhibited ST‐T alternans and the associated excitation and conduction abnormalities. The effects of these two drugs cannot be explained on the basis of attenuation of the decrease in the resting potential.