Albumin inhibits effects of Cu2+ on autonomic postganglionic transmission of guinea-pig ileum and vas deferens

Abstract

Abstract

The influence of albumin, 4.5 and 45g/l, on the effects of Cu²⁺, 10⁻⁹-10⁻³M, on the neuromuscular transmission of the isolated guinea-pig ileum and vas deferens was investigated. Low concentrations of Cu²⁺, 10⁻⁹-10⁻⁶M, caused a slight and transient increase of the contractile response to direct muscle stimulation of the vas deferens. Albumin at 4.5 g/l inhibited this effect. The basal tone of the ileum increased transiently when Cu²⁺ was added in the presence of albumin, 4.5 g/l. A stimulant action of Cu²⁺, 10⁻⁹-10⁻⁶M, was seen on both organs, when contractions were induced by nerve stimulation. All these effects were inhibited by albumin, 45 g/l. Higher concentrations of Cu²⁺, 10⁻⁵-10⁻⁴ M, increased the basal tone of the ileum and the vas deferens. In the presence of albumin, 45 g/l, this stimulating effect of Cu²⁺ appeared in higher concentrations. The results suggest that Cu²⁺ is more likely to influence the function of neuronal tissues when the concentration of protein is low.