Fig. 3. (A ) The electrophoretic profile and gel scanning of cardiac myosin isozymes from the hearts of normal and malignant hyperthermia–susceptible Landrace pigs with prior halothane challenge. Lane 1: myosin isolated from normal hearts; lane 2: myosin from malignant hyperthermia–affected hearts. V1 and V3 myosin is indicated. Myosin (50 μl per tube) was loaded on each gel. (B ) The myosin adenosine triphosphatase assay for cardiac myosin isolated from the two types of porcine hearts. Animals were diagnosed for malignant hyperthermia susceptibility by halothane contracture test 1–8 months before the experiments. The assay was run on thin-layer chromatography as described in Methods. Lane 1 is the mixture without myosin; lanes 2 and 3 are the mixtures with 1 and 2 nmol of malignant hyperthermia–affected cardiac myosin, respectively; lanes 4 and 5 are the mixtures with 1 and 2 nmol of normal cardiac myosin, respectively. The original spot, adenosine triphosphate (ATP), and adenosine diphosphate (ADP) position are as indicated.