A simple method for fast temperature changes and its application to thermal activation of TRPV1 ion channels

Thermally activated ion channels function as molecular thermometers and participate in other physiological important functions. The mechanism by which they acquire their exquisite temperature sensitivity is unknown and is currently an area of intense research. For this reason, there is a need for diverse methods to deliver controlled temperature stimuli.

We have developed a simple, inexpensive and reliable method to deliver temperature pulses to small volumes surrounding the recording area, which can be either a patch-clamp pipette containing a cell-free membrane with thermally activated channels or a whole cell attached to a pipette.

Here we developed a micro-heater based on resistive heating of a copper filament enclosed in a glass capillary that is capable of delivering fast and localized temperature changes. We validated the performance of the micro-heaters by analyzing the heat-induced activation of TRPV1 thermoTRP channels recorded in inside-out patches and demonstrate the use of the micro-heaters.

The micro-heaters we introduce here are compact, easy to fabricate and to operate. In contrast with bulk solution heaters commercially available, our method is extremely affordable and simple to operate. To the best of our knowledge there are no other similar, commercially available heating methods.

The micro-heater method is simple and should provide a straightforward and rapid experimental tool to study mechanisms in thermally activated ion channels.