Microelectrode measurement of cell membrane potential in isolated hepatocytes attached to collagen

Isolated spherical rat hepatocytes attached to collagen-coated cover slips generate a mean membrane potential (Em) of -78 +/- 9 mV as measured with high-resistance microelectrodes. The recordings were biphasic and were stable for upto 20 minutes. The correlation between external potassium concentration and Em was not linear. Several potassium-channel blockers did not effect the membrane potential. Addition of ouabain added to the incubation solution slowly depolarized the cells. The results indicate a high potassium permeability of the isolated spherical hepatocytes attached to collagen.