Pilocarpine-induced lysosomal enzyme secretion, from bovine trabecular meshwork cells

It has long been held that pilocarpine-induced ciliary muscle contraction causes a mechanical change in the configuration of the trabecular meshwork, thereby increasing its fluid conductance. Though the results of many studies are consistent with this theory, other findings suggest a direct action of pilocarpine on the meshwork. We used cultured bovine trabecular meshwork (BTM) cells to study the cell biological effects of pilocarpine, chemically a weak base, and demonstrated increased vacuolization of the BTM cells after incubation with pilocarpine, reflecting a trapping of the protonated base inside the lysosomes. We also showed that pilocarpine enhanced the release of lysosomal hydrolases into the medium. We hypothesize that this is clinically relevant and that the pilocarpine-induced release of hydrolases modifies the extracellular matrix of the trabecular meshwork, thereby increasing its fluid conductance.