Single-channel currents in isolated patches of plasma membrane from basal surface of pancreatic acini

Abstract

Precise localization and characterization of conductance pathways in glandular epithelia have so far proved difficult1. The patch-clamp technique for high resolution current recording2–4, which has already been applied successfully to a number of electrically excitable cells3,4, can in principle overcome these difficulties. We now report measurements of single-channel currents from isolated patches of plasma membrane (inside-out) from the baso-lateral surface of collagenase-isolated rat and mouse pancreatic acini. We have identified a cation channel having a conductance of ∼30 pS and a mean open time in the range 0.3–1 s which is dependent on internal calcium. The single-channel current–voltage relationship is linear and the mean open time independent of the membrane potential. These channels may, at least in part, account for the Ca2+-mediated neural and hormonal control of pancreatic acinar membrane conductance, which is probably responsible for the Ca2+-dependent acinar fluid secretion5–7.