EFFECTS OF DANTROLENE ON THE DIAPHRAGM MUSCLE OF THE NORMAL AND MYOPATHIC HAMSTER

Dantrolene is the only known effective treatment for malignant hyperth ermia. However, its effects on the myopathic diaphragm remain unknown. The effects of dantrolene 10(-8) to 10(-4) mol litre(-1) on diaphragm muscle strips in normal (n=12) and myopathic hamsters (n=13) were inv estigated in vitro in response to tetanic stimulation. We studied cont raction under isotonic and isometric conditions. Data are presented as mean (SD) percent of baseline. Dantrolene induced a negative inotropi c effect in normal and myopathic hamsters but no significant differenc e was observed between groups (active force at 10(-4) mot litre(-1): 3 4 (7) vs 32 (11) %; ns). We conclude that dantrolene induced a compara ble negative inotropic effect on diaphragm muscle in normal and myopat hic hamsters.