Hyperpolarization produced by methohexitone in the chick biventer cervicis skeletal muscle

The effect of methohexitone on endplate potential and on depolarizations produced by acetylcholine (ACh) and tetraethylammonium (TEA) was studied in the isolated chick biventer cervicis skeletal muscle using a sucrose-gap recording technique. Methohexitone (5.5-180 uM) produced concentration-dependent hyperpolarization in the chick skeletal muscle without producing an initial contracture. Methohexitone had a differential effect on the depolarizations produced by ACh (5.5 uM- 11 mM) and TEA (0.95- 48 mM); it greatly reduced the ACh whereas it increased the TEA-induced responses. It was suggested that methohexitone had a dual postjunctional action, but a presynaptic effect was not ruled out.