Figure 2

Carbachol induces pigment granule dispersion in isolated RPE. RPE were isolated from bluegill and, following treatment with forskolin to induce aggregation, were subjected to increasing concentrations of either carbachol or the M1 receptor agonist 4-[N-(4-chlorophenyl) carbamoyloxy]-4-pent-2-ammonium iodide (n = 4 at each concentration, except as noted for carbachol). Both agonists induced dose-dependent, saturable pigment granule dispersion with the former eliciting maximal dispersion at concentrations as low as 1 nM and the latter at concentrations as low as 10 nM. In contast, the M2 agonist arecaidine but-2-ynyl ester tosylate did not effectively stimulate pigment granule dispersion (see Table 2).