Abstract
1. The patch-clamp technique, both cell attached and inside-out patches, was used to examine the effects of lysylbradykinin (LBK) and A23187 on ion channels in cultured Colony 29 epithelial cells derived from a human adenocarcinoma. 2. LBK and A23187 applied directly to the intact cell stimulated the opening of a number of types of ion channel including Ca(2+)-activated K+ channels. 3. By use of inside-out patches, anion channels could be stimulated to open by application of protein kinase A and ATP to the cytosolic surface. Ca(2+)-activated K+ channels were also identified in isolated membrane patches. 4. The results suggest that the anion secretion which is stimulated by LBK is a complex event, involving the activation of a number of different types of ion channel, and that part of the response is the result of hyperpolarization of the cell by activation of Ca(2+)-activated K+ channels. From the data presented in this and the accompanying papers it appears that the Ca(2+)-sensitive K+ channels would be equally effective in either the apical or basolateral membranes.