Whole-cell voltage clamp and intracellular perfusion technique on single smooth muscle cells.

Using freshly isolated single smooth muscle cells prepared by collagenase treatment, membrane currents were recorded by whole-cell voltage clamp. Intracellular constituents were modified by using an intracellular perfusion technique, i.e., pipette solutions were continuously exchanged from control to test solutions during current recording. In smooth muscle cells, intracellular application of ATP, but not cyclic AMP, enhanced the amplitude of Ca2+ currents and prevented current run-down. In addition, with this stabilization of Ca2+ current recording by ATP, introduction of various chemicals into the cell using the intracellular perfusion technique is useful for investigations of regulation of ion channels in smooth muscle cells.