['Malignant hyperthermia (MH) results from disordered calcium (Ca(2+)) homeostasis in skeletal muscle during general anesthesia. Although Ca(2+) channel blockers may be given to treat the tachycardia and circulatory instability, coadministration of Ca(2+) channel blockers and dantrolene is contraindicated during MH crisis. We evaluated the effect of Ca(2+) channel blockers on Ca(2+) homeostasis and their interactions with dantrolene in human skeletal muscle.', 'Human skeletal muscle samples were obtained by biopsy and divided into two groups according to the results of the Ca(2+)-induced Ca(2+) release rate test. Differentiated myotubes were labeled with Fura-2, and changes in the 340/380-nm ratio were used to calculate changes in Ca(2+) concentration following nifedipine treatment in the absence or presence of dantrolene.', 'Nifedipine induced a transient increase in the intracellular Ca(2+) concentration ([Ca(2+)](i)) in a dose-dependent manner. The half-maximal concentration (EC(50)) for nifedipine was 0.718\xa0±\xa00.329\xa0μM in the accelerated group and 1.389\xa0±\xa00.482\xa0μM in the nonaccelerated group (P\xa0=\xa00.009). The addition of 50\xa0μM dantrolene attenuated by 15.4% the increase in [Ca(2+)](i) caused by the 0.5\xa0μM nifedipine.'] Are calcium channel blockers inadequate for malignant hyperthermia crisis?