Patch-clamp measurements of elementary chloride currents activated by the putative inhibitory transmitter GABA and glycine in mammalian spinal neurons.

Methods for measuring whole-cell and unitary Cl- currents in the soma membrane of cultured spinal cord neurons by the patch-clamp technique are described. To separate single channel Cl- currents activated by the two putative inhibitory transmitters GABA and glycine from other membrane currents, isotonic KCl pipette solutions are used for measurements on "cell-attached" membrane patches. To isolate unitary Cl- currents in "cell-free" membrane patches, symmetrical, isotonic Tris Cl- solutions are used in both the pipette and the bath. Single Cl- channels are opened following binding of two agonist molecules to their respective receptors. The gating behavior of single receptor-channel complexes is described in terms of the activation and desensitization mechanism suggested originally by del Castillo and Katz (1957) and Katz and Thesleff (1957).