Earthworm muscle preparation for studying several potent compounds--the possible existence of a "Soman receptor.".

A new model of earthworm (Eisenia foedida) dorsal muscle preparation was studied. It is a specific preparation for testing GABA and its agonist muscimol. The response of muscle could be recorded through mechanical functional changes instead of potential variations. Thus, it is a direct and simple means for measuring GABA activity. ChE-deactivated preparation was suggested for this purpose. By mild membrane modifications of earthworm muscle preparation, it was possible to remove or inactivate GABA, glutamic acid or Soman combining protein. In conjunction with superfusion of Ach-receptor antagonist (alpha-Bungaratoxin) or GABA antagonist (picrotoxin, isopropylbicyclophosphate), we could differentiate Soman receptor from Ach and GABA receptor. The possible existence of a Soman receptor in the earthworm muscle was therefore proposed.