An inwardly rectifying K+ channel in human adenomatous parathyroid cells

The ion channel populations of cells prepared from human adenomatous parathyroid glands have been investigated using standard patch-clamp techniques with pipettes containing isotonic K(+)-rich solutions. The principal channel type observed was an inwardly rectifying K+ channel of 35 pS conductance. In addition, we have frequently observed a lower conductance (12 pS) K+ channel that appeared to conduct current in both directions. In addition to these K+ channels, we have observed non-selective cation channels and possibly CI- channels. Although we have observed occasional current transitions that might have arisen from a large conductance K+ channel similar to that observed in rat and bovine parathyroid cells, we have not been able positively to identify such a channel in human parathyroid cells, either in cell-attached or in excised inside-out patches.