A temperature and solution control system for the measurement of single channel currents in excised membrane patches

A technique is described which permits accurate temperature control and relatively rapid temperature changes (within about 2 min for 10 degrees C changes between 10 degrees and 40 degrees C) of the solution perfusing the exposed surface of excised membrane patches. The simultaneous exchange of temperature controlled solution is also possible. Using the "sleeve technique", patches excised from cells in standard tissue culture dishes are removed to a separate chamber where temperature and solution are accurately controlled. This avoids two common limitations of existing temperature or solution control systems: (1) test solution contamination of the tissue perfusion solution which may impair cell viability and (2) the use of specialised chambers which are unsuitable for use with cultured cells. In the system described, temperature control is possible over the range of at least 4-40 degrees C. Desired temperatures can be preset to within approximately +/- 1 degrees C, and can then be controlled and measured to an accuracy of +/- 0.1 degree C. At a constant temperature, the system enables rapid solution changes, the solution bathing the excised patch being exchanged in approximately 3 s.