Halothane alters cytosolic calcium transient in tracheal smooth muscle.

Academic Article

Abstract

  • Halothane is a potent bronchodilator that attenuates vagally mediated constriction of canine airways, in part by a direct action on the smooth muscle cell. In tracheal smooth muscle, acetylcholine (ACh) produces a transient peak increase in cytosolic ionized calcium concentration ([Ca2+]i), which declines to a sustained plateau concentration that is higher than that of the unstimulated muscle, and a sustained increase in force. The transient peak [Ca2+]i is caused primarily by Ca2+ release from the sarcoplasmic reticulum (SR), whereas the plateau [Ca2+]i is caused primarily by influx of extracellular Ca2+ across the plasma membrane. This study was conducted to investigate the effects of halothane on the 1) transient peak [Ca2+]i during force development (i.e., developed force) and 2) plateau [Ca2+]i during force maintenance (i.e., sustained force) induced by ACh in isolated strips of canine tracheal smooth muscle. Changes in [Ca2+]i were measured with the photoprotein, aequorin. In muscle strips contracted after incubation with 1.1 (n = 5) or 1.5 (n = 5) minimum alveolar concentration (MAC) halothane, halothane significantly attenuated the transient peak aequorin luminescence (AL) and developed force and significantly prolonged the time necessary to reach peak AL and developed force; these effects were not dose dependent. In muscle strips (n = 3) contracted with ACh, addition of halothane caused a reduction in sustained force but no decrease in plateau AL.(ABSTRACT TRUNCATED AT 250 WORDS)
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    Published In

    Keywords

  • Acetylcholine, Aequorin, Animals, Calcium, Cytosol, Dogs, Electrophysiology, Halothane, In Vitro Techniques, Luminescent Measurements, Muscle Contraction, Muscle, Smooth, Trachea
  • Digital Object Identifier (doi)

    Author List

  • Jones KA; Housmans PR; Warner DO; Lorenz RR; Rehder K
  • Start Page

  • L80
  • End Page

  • L86
  • Volume

  • 265
  • Issue

  • 1 Pt 1