Biophysical and pharmacological characterization of ligandgated ion channels in multi-hole mode
The multi-hole patch clamp technology for the QPatch enables gigaseal recordings of up to ten cells patch-clamped on a single measurement site. In this set of experiments, we have convincingly demonstrated that multi-hole QPatch experiments of fast and slow desensitizing ligand-gated ion channels perform as well as single-hole QPatch experiments with respect to both biophysical and pharmacological characteristics. In the QPlate X, the ten patch holes have a relatively wide spatial distribution to avoid intercellular contact and downstream space clamp issues. The wide spatial distribution could, on the other hand, potentially slow down the liquid exchange times. We examined the glutamate receptor GluR5, the nicotinic acetylcholine receptor nAChR α1, the acid-sensing ion channel ASIC1a, and the anionic γ-aminobutyric acid receptor A GABA-A α1β2γ2 with regards to agonist rise-time, reversal potential and pharmacological properties on the QPatch HTX in multi-hole mode and compared to results obtained in the classic single-hole mode. All data clearly demonstrate that while the amplitude of the elicited ion channel current is multiplied by a factor of 7-10, and the successrate in terms of usable current amplitude is increased, other significant biophysical properties of these ion channels remain unaltered.