Coupling ratio of electrogenic Na+-alanine cotransport in isolated rat hepatocytes

Na+-alanine cotransport across the cell membrane in isolated rat hepatocytes was studied. Changes in the cell membrane potential associated with the transport of alanine interfere with determination of the Na+-alanine coupling ratio of the cotransport. With valinomycin present to ‘clamp’ the cell membrane potential, a coupling ratio of 1:1 for the Na+-alanine influx was obtained.