Planar Lipid Bilayer Electrophysiology of Opioid Peptides

For planar lipid bilayer electrophysiology measurements, a constant voltage of −70 mV was applied over a single nanopore, and a buffer solution containing 1M KCl buffered to pH 3.8 using 50mM Citric acid titrated with bis-tris-propane was used. [Met5]-Enkephalin and [d-Ala2][d-Leu5]-Enkephalin (Sigma Aldrich) were added in 10μM concentration. Ionic currents were recorded using an Axopatch 200B amplifier coupled with a Digidata 1440a or Digidata 1550B A/D converter (Molecular Devices). All data was recorded using Clampex 10 (Molecular Devices) with a sampling frequency of 50 kHz and an analog Bessel filter of 10 kHz. Measurement procedures were first described in (Lucas et al., 2021 (link)).