SummaryA 26‐year‐old asthmatic female developed severe asthma within a few hours of receiving three oral doses of 0.4 mg ergometrine maleate for the control of postpartum haemorrhaging. This experience and two previous reports of bronchospasm in asthmatic subjects following ergometrine suggested that ergometrine altered airway smooth muscle tone.In the present investigation the effect of ergometrine was studied on canine tracheal smooth muscle strips. Ergometrine (10−9m10−8m) induced contraction of canine tracheal smooth muscle. The concentration causing 50 of maximal contraction (EC50) was 4.73 × 10−8M. The acetylcholine EC50was not altered by ergometrine (10−9M or 10−8M); however, acetylcholine (10−4mand 10−3m) induced contractions were enhanced by ergometrine (10−8m). The data suggest that ergometrine maleate may cause broncho‐constriction in som
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