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Comparison of the chronic and acute effects of amiodarone on the calcium and potassium currents in rabbit isolated cardiac myocytes
Author(s) -
Varró András,
Virág László,
Papp Julius Gy.
Publication year - 1996
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.1476-5381.1996.tb16713.x
Subject(s) - amiodarone , medicine , inward rectifier potassium ion channel , potassium , myocyte , calcium , electrophysiology , cardiology , chemistry , endocrinology , pharmacology , anesthesia , ion channel , atrial fibrillation , receptor , organic chemistry
1 The acute and chronic effects of amiodarone were studied on the transmembrane ionic currents in rabbit single ventricular myocytes at 35 ° C by applying the whole‐cell configuration of the patch‐clamp technique. 2 Acute exposure to 1 and 5 μ amiodarone significantly reduced the amplitude (‐53.9±3.9%, n = 5 and −64.0±2.0%, n = 3, P <0.01), but chronic amiodarone treatment (i.p. 50 mg kg −1 day −1 for 3–4 weeks) changed neither the amplitude nor the kinetics of the inward calcium current. 3 Both acute superfusion with amiodarone (1 and 5 μ) and chronic amiodarone treatment significantly decreased the amplitude of the delayed rectifier outward potassium current ( I k ). 4 Acute application of amiodarone (1 and 5 μ) did not alter but chronic amiodarone treatment moderately depressed the transient outward current ( I to ). 5 Neither the acute (1 and 5 μ) nor the chronic amiodarone treatment changed the magnitude of the inward rectifier potassium current ( I k1 ). 6 It is concluded that acute amiodarone application and chronic amiodarone treatment alter transmembrane ionic currents of ventricular myocytes differently. This may explain, at least in part, the marked differences in the cardiac electrophysiological effects observed after acute and chronic amiodarone treatment in patients.