Zinc reduces the electrophysiological responses in vitro to basolateral receptor mediated secretagogues in piglet small intestinal epithelium

Dietary zinc treatment has a preventive impact on diarrhoea in newly weaned piglets and in undernourished children. The mechanisms behind this effect of zinc are however, still not fully understood. The aim of the present study was to assess if zinc has a direct effect on porcine intestinal secretory responses to different secretagogues in vitro. The study included two Ussing chamber experiments, where the short circuit current responses to different secretagogues were measured in piglet small intestinal epithelium. Exp. 1 aimed to study the effect of increased zinc concentrations in the bathing media on the secretory responses to 5-HT and theophylline. The objective of exp. 2 was to study the effect of zinc in the bathing media on the secretory responses induced by vasoactive intestinal polypeptide (VIP), Substance P (SP), Carbachol, and theophylline. The results showed that there were significant decreasing effects of zinc on the secretion, stimulated by 5-HT, VIP and carbachol, from piglet intestinal epithelium in vitro, whereas the secretion caused by SP and theophylline was not significantly affected. The data indicate that the inhibitory mechanism of zinc ions may take place at the receptors situated at the basolateral membrane of the epithelial cells.