Receptors for C-type natriuretic peptide in cultured rat glial cells

To characterize sites of action of C-type natriuretic peptide (CNP) in the glial cells, the effect of CNP on cGMP accumulation and the binding of [125I]CNP in rat astrocyte RCR-1 cells were studied. CNP stimulated cGMP accumulation in the cells from 10(-9) M in a dose-dependent manner, but ANP (atrial natriuretic peptide) had a negligible effect on cGMP accumulation in the cells. [125I]CNP was bound to the cells and its Kd value was 2 orders of magnitude lower than that of the ED50 value for stimulation of cGMP accumulation in the cells. Not only CNP but also ANP displaced [125I]CNP binding to the cells. These results suggest that RCR-1 cells have a B-receptor which contains a guanylate cyclase domain and is preferentially activated by CNP, and that they also have a C-receptor which does not contain a guanylate cyclase domain that reacts with both ANP and CNP.