Porcine malignant hyperthermia: effects of temperature and extracellular calcium concentration on halothane-induced contracture of susceptible skeletal muscle.
Skeletal muscle from malignant hyperthermic (MH) pigs incubated at 37 C in 2.3 mM calcium-Krebs-Ringer solution contracts spontaneously when exposed to halothane. In contrast, halothane did not induce contracture in MH muscle incubated in 2.3 mM calcium-Krebs-Ringer solution at 25 C or in calcium-free Krebs-Ringer's solution at 37 C. Halothane did not induce contracture in normal control muscle in 2.3 mM Krebs-Ringer solution at 25 or 37 C. In the presence of halothane, addition of caffeine produced greater contracture in MH muscle than in normal controls. Halothane-caffeine-induced contractures of MH and control muscles at 25 and 37 C were similar. Elucidation that under certain experimental conditions halothane induces contracture in MH muscle, but not in normal muscle 1) may aid in development of a diagnostic test; 2) establishes further evidence for skeletal muscle as the target tissue for anesthetic-induced MH; 3) suggests that halothane may affect systems that regulate sarcoplasmic calcium concentration below contracture threshold in MH muscle. (Key words: Hyperthermia, malignant; Anesthetics, volatile, halothane; Ions, calcium; Muscle, skeletal, malignant hyperthermia.).
D000818:Animals; D002110:Caffeine / Q000008:administration & dosage / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006221:Halothane / Q000008:administration & dosage / Q000494:pharmacology*; D066298:In Vitro Techniques; D008305:Malignant Hyperthermia / Q000175:diagnosis / Q000503:physiopathology*; D009119:Muscle Contraction / Q000187:drug effects*; D009132:Muscles / Q000187:drug effects; D013552:Swine; D013696:Temperature; D013997:Time Factors; D014159:Transducers
D002110:Caffeine; D002118:Calcium; D006221:Halothane