The functional EC
50 values obtained for bimatoprost in TM cells, SC cells, and CSM cells are consistent with the presence of a bimatoprost-sensitive receptor population.
29–33 Bimatoprost in amide form exhibits no meaningful activity at FP receptors, whereas PGF
2α and its anionic analogs, such as 17-phenyl PGF
2α and fluprostenol, typically have functional EC
50 values in the low nM range.
29,31–35 Where prostamide activity coexisted with FP receptor expression in the present study, bimatoprost and anionic PGF
2α analogs were essentially equipotent
30–33 when comparing bimatoprost, fluprostenol, and 17-phenyl PGF
2α in CSM cells. In TM and SC cells, bimatoprost was actually more potent than 17-phenyl PGF
2α and fluprostenol, respectively. In contrast, the functional EC
50 values obtained for 17-phenyl PGF
2α in the rabbit uterus, feline iris, and human ocular cells were essentially the same.
29,31 Bimatoprost has, however, been reported as slightly more potent than 17-phenyl PGF
2α in the feline lung parenchymal assay.
30 The reasons for these differences in potency between cell types and tissues are likely related to their respective PG receptor populations.