Evidences for possible existence of a “soman receptor” in earthworm dorsal muscle

GABA, glutamic acid or soman binding sites could be inactivated or removed from the earthworm muscle cell membranes by means of incubating at 40 degrees for 50 min, treating with 10% (NH4)2SO4 (60 min) or 1% Triton X-100 (30 min), without affecting the function of Ach binding sites. ChE activity of the modified muscle pieces was much more active than that of the normal ones. It indicated that AChE also remained intact on the membrane during the above mentioned treatments. Therefore, muscular contractions induced by Ach were evidently enchanced so long as the enzyme was inhibited after the addition of soman.
Soman binding effects could be well distinguished on the superfused muscle preparations from the effects of Ach, GABA, and Glu by using bungarovenom or picrotoxin and isopropyl bicyclophosphate or apomorphine as antagonists against these 3 putative neurotransmitter receptors respectively.
Based on the above results, the possible existence of a “soman receptor” in the earthworm muscle was proposed.