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

Precise localization and characterization of conductance pathways in glandular epithelia have so far proved difficult¹. The patch-clamp technique for high resolution current recording^2-4, which has already been applied successfully to a number of electrically excitable cells ^3,4, 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 secretion^5-7.