Dantrolene does not block calcium pulse-induced calcium release from a putative calcium channel in sarcoplasmic reticulum from malignant hyperthermia and normal pig muscle.

Calcium pulse additions to isolated SR membranes can cause a reversible efflux of calcium. The threshold level of calcium loading at which calcium efflux occurs is lower for SR membranes isolated from malignant hyperthermia susceptible (MHS) swine. Dantrolene, a unique muscle relaxant, had no effect on threshold calcium load, amounts and rates of calcium release from SR isolated from control and MHS skeletal muscle. It is concluded that the putative calcium channel through which this calcium pulse-induced calcium release mechanism occurs is not affected by dantrolene under these experimental conditions.