Effect of Acetylcholine on the Electrical Activity of Cultured Chick Embryonic Heart

The spontaneous mechanical activity of the cultured chick embryonic auricle is inhibited to a considerable extent by acetylcholine (ACh) (1), while the mechanical and electrical activities of cultured ventricle is practically unaffected by the drug (1, 2). The difference of snesitivity to ACh between the auricle and ventricle may be due to the presence or absence of cholinergic innervation, which may increase the sensitivity to ACh. On the other hand, many investigators suggest that ACh increases the permeability of the cell membrane to K+, and allows the resting potential to come near the K+-equivallent potential (3-5). It would be neccessary to study the effect of ACh on the intracellular membrane potential of auricle, because the cultured cells were often completely excitationcontraction uncoupled (6). The cultured preparation enables one to study the effect of ACh on the cell membrane potential without interfering with the nerve component or neighbor cells Jellinek et al. (7) demonstrated the absence of nerve tissue in the cultured cell clusters and Dahaan and Gottlieb (8) observed no electrical interaction among conjoint cells.