A system for applying rapid warming or cooling stimuli to cells during patch clamp recording or ion imaging

We describe a system for superfusing small groups of cells at a precisely c ontrolled and rapidly adjustable local temperature. Before being applied to the cell or cells under study, solutions are heated or cooled in a chamber of small volume (similar to 150 mul) and large surface area, sandwiched be tween four small Peltier elements. The current through the Peltier elements is controlled by a microprocessor using a PID (proportional-integral-deriv ative) feedback algorithm. The chamber can be heated to at least 60 degrees C and cooled to 0 degreesC, changing its temperature at a maximum rate of a bout 7 degreesC per second; temperature ramps can be followed under feedbac k control at up to 4 degreesC per second. Temperature commands can be appli ed from the digital-to-analogue converter of any laboratory interface or ge nerated digitally by the microprocessor. The peak-to-peak noise contributed by the system does not exceed that contributed by a patch pipette, holder and headstage, making it suitable for single channel as well as whole cell recordings. (C) 2001 Elsevier Science B.V. All rights reserved.