|Temperature control can many times be extremely important to the quality of the experimental results. The following application example demonstrates the benefits of combining temperature control with voltage clamping.|
Two-Electrode Voltage Clamp in Oocytes from Xenopus Laevis
Ionic currents expressed in Xenopus oocytes at two temperatures following microinjection of cRNA coding for the Drosophila Shal potassium channel (Wei et al., 1990, Science 248, 599-603). The membrane potential was stepped from -80 mV to +20 mV in 20 mV intervals. The holding potential was -90 mV, and the currents were filtered at 1 KHz. The rates of channel activation and inactivation are both significantly faster (Q10 > 4) near room temperature. The current traces, which are not corrected for the capacity transient, show that the rising phase of the potassium current can be better resolved at lower temperatures.
As you can clearly see, the kinetics of the potassium currents depend strongly on the temperature (peak current of 0.975 at 22° C, is almost double the current of 0.510 µA measured at 15° C), and the effect is larger than expected from the usual shift in kinetics seen when the temperature is changed. The rate of activation and inactivation are both much faster near room temperature. Such current traces show why it is important to control the temperature of the experimental chamber with a device such as the Dagan TC-10 Temperature Controller.
Current records using a Dagan TEV-200 Two Electrode Voltage Clamp, were provided by Dr. Manuel Covarrubias, Jefferson Medical College, Philadelphia, PA.
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Warning: This equipment is not intended for use in human applications or human experimentation.
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