Premium
Inhibitory effects of halo thane on high K+–induced canine tracheal smooth muscle contraction and intracellular Ca 2+ increment
Author(s) -
YAMAKAGE M.,
KAWAMATA T.,
KOHRO S.,
NAMIKI A.
Publication year - 1994
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.1994.tb04011.x
Subject(s) - halothane , isometric exercise , contraction (grammar) , intracellular , muscle contraction , medicine , biophysics , muscle tension , endocrinology , anatomy , anesthesia , chemistry , biochemistry , biology , physical medicine and rehabilitation
Halothane is a potent bronchodilator. The effects of halothane on isolated canine tracheal smooth muscle contraction and intracellular Ca 2+ increment induced by a high concentration of K + were investigated to clarify how this anaesthetic decreases intracellular Ca 2+ concentration ([Ca 2+ ]i), an important second messenger. The tension of the muscle strips was measured using an isometric transducer, and [Ca 2+ ]i was measured using a surface fluorescence spectroscopy. Exposure to a 72.7 mM K + solution increased muscle tension and [Ca 2+ ]i. Halothane (1,2,3 and 4% at the vaporiser) was introduced by bubbling in the presence of the 72.7 mM K + , and significantly decreased both this elevated muscle tension and the [Ca 2+ ]i in a concentration–dependent manner. Similarly, slowly decreasing concentrations of K + (48.5, 36.4, 24.2 and 18.2 mM) significantly decreased both of these variables. There was no significant difference between the slopes of the two regression lines of changes in muscle tension and changes in [Ca 2+ ]i. From the evidence that tonic increase in [Ca 2+ ]i by high concentrations of K + is due to the influx of Ca 2+ via L–type voltage channels, halothane may modify the L–type channels to decrease Ca 2+ influx. In conclusion, halothane inhibits the high K + –induced canine airway smooth muscle contraction by decreasing [Ca 2+ ]i. The decrease in [Ca 2+ ]i by halothane might be due to inhibition of voltage–operated channels, especially the L–type channels.