Patch-Clamp Measurements of Elementary Chloride Currents Activated by the Putative Inhibitory Transmitters 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).
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