AbstractThe ethanolic extracts of the leaves and stembark ofBridelia ferrugineawere separately investigated for their effects on skeletal muscle using the phrenic nerve‐hemidiaphragm muscle preparation from rats. The bark extract inhibited twitch tension induced by direct electrical stimulation (muscle) (MS) but not indirect electrical stimulation (nerve) (NS) of the diaphragm. It inhibited tetanus tension to both nerve (TNS) and muscle stimulation (TMS), had no effect on K+‐induced contracture and reduced the minimal fusion frequency (MFF). The leaf extract had no effect on twitch tension to NS and MS or K+‐induced contracture but increased tetanus tension to TNS or TMS as well as MFF. These findings suggest that the bark extract does not affect influx of extracellular Ca2+but inhibits the intracellular mobilization of Ca2+. The leaf extract also had no effect on influx of extracellular Ca2+but most likely facilitated the intracellular mobilization of Ca2+. Thus, the intracellular action of the bark extract is opposite to that of the leaf ex