The lowest stimulatory concentrations of pyridines that induced larvae of <i>C. teleta</i> to metamorphose compared with the K_M of these same chemicals on the pyridine-activated ion channel of the crayfish <i>A. torrentium.</i>

The concentration of 4-acetylpyridine that inhibited 50% of the larvae of C. teleta is also compared with the IC50 of 4-acetylpyridine for the crayfish (adapted from Hatt and Schmiedel-Jacob, 1984). The lowest stimulatory concentrations of pyridines that induced larvae of C. teleta to metamorphose compared with the KM of these same chemicals on the pyridine-activated ion channel of the crayfish A. torrentium.