A patch-clamp study on a novel gamma-aminobutyric acid activated chloride channel of crayfish deep extensor abdominal muscle.

The patch-clamp technique was used to study the effect of rapid pulses of gamma-aminobutyric acid (GABA) on excised membrane-patches in the outside-out configuration of the deep extensor abdominal muscle (DEAM) of crayfish. Channel currents reversed at the equilibrium potential of Cl- and were blocked by picrotoxin. Rare channel openings were elicited by 0.1 mM GABA, and a saturating open probability of 0.9 was reached with 10 nM GABA. The investigated channel was only sensitive to GABA and is different from a previously described GABAergic channel in crayfish that is in addition sensitive to acetylcholine and glutamate and shows three subconductance states.