Receptors for atrial natriuretic peptide (ANP) and cyclic GMP responses in HeLa cells

Cultured HeLa cells display specific binding sites for atrial natriuretic peptide (ANP). Studies with [125I]-(1-28)-rat ANP revealed the presence of a single class of high affinity binding sites on HeLa cells: The apparent dissociation constant (Kd) was 5 nM and the maximal number was 29,000 sites/cell as derived from Scatchard analysis. Furthermore, ANP elevates levels of cGMP in a dose dependent manner with an EC50 close to the Kd for [125I]ANP binding. ANP-mediated elevation of cellular cGMP leads to a significant reduction of bumetanide-sensitive Na+, K+, 2Cl(-)-cotransport in HeLa cells, studied by 22Na+ and 86Rb+ influx measurements. These data indicate (1) that distinct functionally active receptors for ANP are present on HeLa cells and (2) ANP influences the activity of Na+,K+,2Cl(-)-cotransport in these cells.