Malignant hyperthermia (MH) is a hereditary myopathy, triggered when susceptible patients are exposed to a depolarizing muscle relaxant and/or potent volatile anesthetics. We have studied the effects of dantrolene on the free [Ca2+]i of intercostal muscle biopsies obtained from two MH‐susceptible patients before and after administration of dantrolene orally (2.5 mg/kg for 3 days) and intravenously (1.0 mg/kg 2 hours before the biopsy). The free [Ca2+]i was measured by Ca2+‐selective microelectrodes. The mean resting free [Ca2+]i in the MH‐susceptible muscle before dantrolene treatment was 0.42 ± 0.01 μM (mean ± SEM, n = 12). The administration of dantrolene reduced this value to 0.27 ± 0.01 μM (n = 14). There was no detectable difference in the resting membrane potential after dantrolene. These results represent the first direct demonstration that dantrolene is able to reduc the resting free [Ca2+]i in skeletal muscle of MH‐susceptible patients.
ASJC Scopus subject areas
- Clinical Neurology
- Cellular and Molecular Neuroscience
- Physiology (medical)