Pipette Internal Perfusion: Methods and Applications

The patch-clamp technique has revolutionized the understanding of ion channel physiology (Hamill et al., 1981 ; Neher and Sakmann, 1976 ). This technique facilitates the measurement of currents and voltage in cells under voltage-clamp and current-clamp conditions. Cells can be patched in a variety of configurations. Whole-cell currents and voltage can be measured by forming a high resistance seal between the cell membrane and the rim of the glass or quartz patch pipette. In the whole-cell configuration the seal is ruptured to gain access to the cell interior. Resistive and capacitive currents are dissociated by instantaneously changing the voltage between the cell interior and the bath electrode, and changes in current could be recorded using the classical voltage-clamp approach (Hodgkin and Huxley, 1952 ). Current injections can be used to generate action potentials from excitable cells (Bhatnagar, 1997 ). In addition, single-channel activity can be recorded from both cell-attached and excised patches (Hamill et al., 1981 ).