Ligand-specific temperature-dependent shifts in EC50 values for the GABAA receptor.
We introduce a system for temperature control of a commercial microfluidic superfusion device that, in combination with patch-clamp, enables rapid acquisition of dose-response data at different temperatures. We obtained dose-response curves for the GABAA receptor, a ligand-gated ion channel, for two different agonists at temperatures between 25 and 40 degrees C. For GABA, the dose-response curves shifted toward higher EC50 values as the temperature increased, whereas for beta-alanine, the EC50 values were constant. This shows that temperature is an important factor for obtaining accurate estimations of EC50 values and also that such temperature effects can be ligand-specific. Using the EC50 values, we estimated the enthalpy of dissociation between the ligand and the receptor. Furthermore, the technology introduced here is generally applicable to all patch-clamp studies where temperature control is desirable, e.g., studies of kinetics and thermodynamics, drug screening, compliant ADME/Tox testing, and in studies of temperature-gated ion channels.
Millingen
Maria
M
Department of Chemical and Biological Engineering, Physical Chemistry, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
Bridle
Helen
H
Jesorka
Aldo
A
Lincoln
Per
P
Orwar
Owe
O
D000818:Animals; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D058785:GABA-A Receptor Agonists; D007700:Kinetics; D008024:Ligands; D044085:Microfluidics; D018408:Patch-Clamp Techniques; D051381:Rats; D011963:Receptors, GABA-A / Q000737:chemistry / Q000378:metabolism*; D013696:Temperature; D013816:Thermodynamics; D015091:beta-Alanine / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology
D058785:GABA-A Receptor Agonists; D008024:Ligands; D011963:Receptors, GABA-A; D015091:beta-Alanine; D005680:gamma-Aminobutyric Acid