Intracellular perfusion of Xenopus oocytes

This chapter describes a method for recording macroscopic voltage clamp currents through the membrane of intracellularly perfused Xenopus oocytes. The method allows full control of the solutions bathing the membrane. The potential importance of the internal perfusion method is enhanced by the widespread use of Xenopus oocytes for the heterologous expression of wild type and mutated ion channels. A major problem in the internal perfusion method is the lack of an accurate estimate of the seal resistance. The current flowing through the shunt resistance of the seal may influence or even distort the recording of the current flowing through the membrane, if seal resistance is insufficiently high. If there is only a loose seal at the edges of the contact of the glass with the membrane, the voltage control is poor, and this distorts the recorded current. A rigorous test of the validity of the method for measuring fast currents is yet to be performed.