Malignant hyperthermia: an altered phospholipid and fatty acid composition in muscle membranes.

There is thought to be a genetic defect within the calcium release channel of the sarcoplasmic reticulum in malignant hyperthermia (MH). This primary alteration is hypothesized to influence the function and/or structure of various muscle membrane systems; e.g., to have a direct effect on the composition of the lipid matrix. Therefore, in striated muscle samples, we determined the quantity and fatty acid composition of the various types of membrane phospholipids. German Landrace pigs were classified as normal or susceptible to MH. Total lipid content from longissimus dorsi, semi-membranosus muscle, and heart left ventricular (HLV) samples were extracted with chloroform/methanol and subsequently separated by high performance liquid chromatography. The single phospholipid fractions were collected and, following derivatization, the quantities of individual fatty acids were determined using a capillary gas chromatographic method. In general, samples from the susceptible pigs contained lower absolute amounts of individual phospholipids. The most notable differences occurred in the HLV, where phosphatidylinositol, phosphatidylserine, phosphatidylethanolamine and sphingomyelin were all significantly less (P less than or equal to 0.05). The muscle from the susceptible animals also contained decreased amounts of the polyunsaturated phospholipid-bound fatty acids (P less than or equal to 0.05). These differences in phospholipid and fatty acid concentrations of membranes isolated from swine susceptible to MH may relate to their apparently increased sensitivities to halothane (e.g., fluidizing effects) or elevated temperature.