PATCH-CLAMP DETECTION IN CAPILLARY ELECTROPHORESIS

We describe a capillary electrophoresis-patch clamp (CE-PC) analysis o f biomolecules that activate ligand-gated ion channels. CE-PC offers a powerful means for identifying receptor ligands based on the combinat ion of the characteristic receptor responses they evoke and their diff erential electrophoretic migration rates. Corner frequencies, membrane reversal potentials, and mean and unitary single-channel receptor res ponses were calculated from currents recorded with patch clamp detecti on. This information was then combined with the electrophoretic mobili ty of the receptor ligand, which is proportional to the charge-to-fric tional-drag ratio of that species. We applied CE-PC to separate and de tect the endogenous receptor agonists gamma-aminobutyrate and L-glutam ate and the synthetic glutamate receptor agonists N-methyl-D-aspartate and kainic acid. We present dose-response data for electrophoreticall y separated kainic acid and discuss its implications for making the CE -PC detection system quantitative.