In this study specific high affinity binding sites for atrial natriuretic factor (rANF(99–126)) have been identified on cultured endothelial cells of bovine pulmonary artery origin (BPAEC). A time-dependent rise in cellular cGMP levels stimulated by rANF(99–126) was followed by release of the nucleotide into the incubation medium. The use of truncated, ring-deleted and linear atrial peptide analogs in competitive displacement analysis and measurement of cGMP accumulation indicated that only a minor proportion (5–11%) of the available receptor pool was of the ANF-B receptor subtype, linked to guanylate cyclase, with the remaining major proportion possibly of the ANF-C (clearance) receptor subtype. The existence of two ANF receptor subtypes in this cell culture model would suggest a significant role for the circulating peptide in modulation of pulmonary endothelial cell function, which would influence or complement its direct actions on the underlying vasculature of the pulmonary circulation.
