AbstractThe behavior of cultured myotubes from chick embryos exposed to microwaves has been experimentally analyzed. Recordings of acetylcholine‐induced currents have been obtained via patch‐clamp techniques using both cell‐attached (single‐channel current recording) and whole‐cell (total current recording) configurations. During the exposure to low‐power microwaves the frequency of the ACh‐activated single channel openings decreased, while the ACh‐induced total current showed a faster falling phase. Channel open time and conductance were not affected by microwave irradiation. It is concluded that the exposure to microwaves increases the rate of desensitization and decreases the channel opening probability. The nonthermal origin and the molecular interaction mechanisms governing these electromagnetic‐induced effects are discussed.