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Effects of halothane on membrane currents associated with contraction in single myocytes isolated from Guinea‐pig ventricle
Author(s) -
Terrar D.A.,
Victory J.G.G.
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.tb11553.x
Subject(s) - halothane , calcium , contraction (grammar) , chemistry , verapamil , ventricle , myocyte , muscle contraction , guinea pig , endocrinology , medicine , biophysics , voltage dependent calcium channel , biology , organic chemistry
1 The effects of halothane on electrical activity and contraction were investigated in single myocytes isolated from guinea‐pig ventricle. 2 Halothane depressed the plateau and shortened the duration of action potentials. 3 Halothane also reduced the amplitude of inward calcium currents and of additional inward current activated by cytosolic calcium under voltage‐clamp conditions. 4 Contractions (measured by an optical technique) accompanying either action potentials or calcium currents were reduced by halothane. However, the extent of attenuation of contraction was greater than when a similar level of calcium channel blockade was induced by application of verapamil. 5 Actions of halothane on calcium‐activated tail currents in double‐pulse experiments were consistent with reduction by halothane of the cytosolic calcium transient, perhaps as a consequence of reduced uptake of calcium into sarcoplasmic reticulum stores. 6 It is concluded that the actions of halothane on inward currents contribute to its effects on action potentials. The reduction in contraction caused by halothane may result partly from a reduced influx of calcium to trigger contraction, and partly by a reduced release of calcium from sarcoplasmic reticulum stores.