Natriuretic peptide receptors on human trabecular meshwork cells

The effects of natriuretic peptides on cGMP formation and [I-125]ANP binding in human trabecular meshwork cells were investigated. CNP at 1 mu M stimulated cGMP formation similar to 18-25 fold, with a half maximal effective concentration similar to 20-30nM. BNP at 1 mu M stimulated similar to 7 fold, while ANP stimulated cGMP formation 2-fold at 1 mu M bur had little or no effect at concentrations below 1 mu M. Displacement binding of [I-125]ANP to intact TM cells in the presence of unlabeled ANP indicated a single binding site with a dissociation constant similar to 0.15nM. c-ANP, which binds specifically to natriuretic peptide C receptors, displaced >95% [I-125]ANP binding to surface receptor sites with a half-maximal effective concentration comparable to that of ANP or BNP. c-ANP had no inhibitory effect on CNP stimulation of cGMP formation. The data suggest that human TM cells possess natriuretic peptide B receptors as the primary guanylyl cyclase-containing subtype and C receptors as the numerically predominant subtype of natriuretic peptide receptors.