The effects of ion changes on the contraction of the rat uterus stimulated by oxytocin.

The contraction of the rat uterus to oxytocin was measured when it was bathed in various solutions. Substitution of nitrate or bromide for two-thirds of the chloride present increased the size of contractions, while a similar substitution of sulphate and sucrose for chloride depressed them. Alteration of the ratio of chloride to sodium by substitution of choline for two-thirds of the sodium present enhanced the contractions, but this was probably due to the choline per se as choline sulphate similarly enhanced the response. Partial replacement of both sodium and chloride by sucrose did not alter the size of contractions.