Rat pancreatic islet cells in primary culture: occurrence of giant cells amenable to patch clamping.

Neonatal and adult rat pancreatic islet cells were maintained in dissociated cell culture for up to three weeks. The unexpected occurrence of giant (40-50 micron) cells was noted, some of which reacted positively to an insulin antiserum, indicating the presence of insulin. The giant cells were amenable to study using the extracellular patch clamp technique, which was used to demonstrate a population of membrane channels gating outwardly directed current in these cells.