Sodium currents in segments of human heart cells

Isolated human heart cells were partially drawn into the lumen of a plastic tube and cleaved at the partitioning tube wall by intraluminal suction pulses. The extraluminal segment (10 to 20 percent of the cell length) was suitable for intracellular perfusion and voltage clamp. The time and voltage dependence of the sodium current, and the responses to changes in driving force and channel blockers, illustrate the potential of these preparations as models for the study of membrane channels.