title: Action of halothane on rat soleus muscle: temperature dependent induction of contractures and modification of caffeine and potassium contractures.
abstract: Halothane induced calcium-dependent contractures in rat soleus muscle at temperatures between 4 degrees C and 13 degrees C, but not at higher temperatures. The peak tension of the contractures increased as temperature was decreased below 13 degrees C. The magnitudes of the contractures were reduced by the addition of cobalt or lanthanum ions to the medium in the water bath. The anaesthetic also potentiated caffeine-induced contractures in muscle at 22 degrees C and 37 degrees C in a calcium-dependent manner. The contractures at 37 degrees C were more sensitive to the concentration of this ion than were contractures at 22 degrees C. Halothane increased peak tension and prolonged the time course of potassium-induced contractures, but did not alter their threshold values at either 22 degrees C or 37 degrees C. It was concluded that, in rat muscle, halothane may act at a site on the plasmalemma, retard the onset of inactivation and move the inactivation curve further from the resting membrane potential.
mesh_terms: D000818:Animals; D002110:Caffeine / Q000494:pharmacology*; D002118:Calcium / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D005260:Female; D006221:Halothane / Q000494:pharmacology*; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects*; D011188:Potassium / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013696:Temperature
chemical_list: D002110:Caffeine; D011188:Potassium; D002118:Calcium; D006221:Halothane