title: Spectrum of susceptibility to malignant hyperthermia--diagnostic dilemma.
abstract: Utilizing established in vitro muscle contracture tests, we have identified three diagnostic contracture phenotypes for malignant hyperthermia susceptibility (MHS) among 103 patients. Phenotype H is an unequivocal diagnostic result for MHS, as is the nonsusceptible phenotype N. The third diagnostic group, phenotype K, represents an equivocal diagnostic response. To provide a basis for understanding relationships between contracture phenotypes and MHS, pigs with phenotypes H, K, and N were exposed to a standardized anesthetic protocol for assessing MHS. During the anesthetic challenge, phenotype H pigs developed a more severe form of the MH syndrome than did phenotype K pigs. Comparing phenotype H v K average responses, VO2 increased four- v twofold; lactate increased 13- v 9-fold; and temperature increased 41.7 degrees C v 39.2 degrees C, respectively. These values either had no change or decreased in the phenotype N pigs. Results of this study suggest that a spectrum of MHS exists among the human population.
mesh_terms: D000818:Animals; D001831:Body Temperature; D002110:Caffeine / Q000494:pharmacology; D004198:Disease Susceptibility / Q000175:diagnosis; D006221:Halothane / Q000009:adverse effects / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D007773:Lactates / Q000097:blood; D019344:Lactic Acid; D008305:Malignant Hyperthermia / Q000175:diagnosis* / Q000235:genetics / Q000503:physiopathology; D009119:Muscle Contraction / Q000187:drug effects*; D010641:Phenotype; D011300:Preoperative Care; D013552:Swine; D013556:Swine, Miniature; D013874:Thiopental / Q000009:adverse effects
chemical_list: D007773:Lactates; D019344:Lactic Acid; D002110:Caffeine; D013874:Thiopental; D006221:Halothane