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Chronotropic effect of nizofenone fumarate in rabbit sino‐atrial node in vitro
Author(s) -
Kotake Hiroshi,
Nawada Takahiro,
Matsumoto Tatsuhiko,
Kitamura Hideyuki,
Kaneda Takafumi,
Hasegawa Junichi,
Mashiba Hiroto
Publication year - 1988
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.1476-5381.1988.tb11753.x
Subject(s) - chronotropic , in vitro , rabbit (cipher) , sinoatrial node , medicine , chemistry , pharmacology , cardiology , endocrinology , heart rate , mathematics , biochemistry , blood pressure , statistics
1 The effects of nizofenone fumarate were studied on the membrane potentials and currents of rabbit sino‐atrial node preparations by means of the double‐microelectrode voltage clamp method. 2 In spontaneously firing pacemaker cells, nizofenone (above 1 μ m ) decreased the heart rate. Above 3 μ m , nizofenone reduced the maximum upstroke velocity, the amplitude of the action potential and the slope of the phase 4 depolarization, and prolonged the action potential duration at 50% repolarization. 3 Under voltage clamp conditions, nizofenone decreased the slow inward current and the time‐dependent potassium outward current in a dose‐dependent manner. 4 These findings suggest that nizofenone exerts an inhibitory action on the automaticity of sinoatrial node preparations via effects on both inward and outward currents.