Calcium uptake in frozen muscle biopsy sections compared with other predictors of malignant hyperthermia susceptibility.

The frozen-section Ca45 uptake procedure of Mabuchi and Sreter has been applied to 51 frozen human muscle biopsies previously tested for halothane and for caffeine contracture responses. In preliminary tests with cat muscle, uptake varied with skeletal muscle fiber type, was absent from smooth muscle, and was blocked by agents which damage or extract sarcoplasmic reticulum. In the human biopsies, however, the calcium uptake values showed no significant correlation with any of the following parameters: time of frozen-biopsy storage up to 5 yr; fiber type distribution; positive versus negative response in the halothane contracture test; positive versus negative response in the caffeine contracture test; positive versus negative response in the combined halothane/caffeine contracture test; and presence of a documented clinical episode of malignant hyperthermia. In contrast, a positive halothane or caffeine contracture test each correlated highly with the presence of a prior clinical episode. We conclude that the evidence fails to support the use of the Ca45 uptake procedure in frozen sections of skeletal muscle biopsies as a valid indicator of malignant hyperthermia susceptibility.