Influence of cadmium ions on the reactivity of isolated human uterine arteries

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Abstract
The isometric contractions were recorded for pieces of uterine arteries as well as ascending branches of uterine artery (1-2 mm diameter) obtained from 36 nonpregnant, premenopausal women undergoing hysterectomy. Contractile responses to K(+)-depolarization, noradrenaline, and Ca+2 ions were studied. Cadmium at concentrations 10(-9)-10(-3) M produced no changes of tension in the investigated arteries. Incubation (15 min) with low concentration of cadmium (10(-9)-10(-7) M) evoked an increase of amplitude of K(+)-induced contractions in 50% of investigated vessels. Cadmium at concentrations of 10(-6)-10(-3) M gradually inhibited contractions. The influence of cadmium on contractions evoked by noradrenaline was similar to those on K(+)-induced contractions. In a Ca(2+)-free medium, 10(-5) M cadmium induced tonic contractions and pretreatment with 10(-7) and 10(-5) M cadmium slightly enhanced Ca(2+)-induced contractions. Cadmium concentration of 10(-4) M caused substantial inhibition of Ca(2+)-induced contractions. The results suggest that in the human uterine vessels cadmium is not only a Ca(2+)-channels blocker but also interferes with intracellular mechanisms involved in excitation-contraction coupling.