Fig. 3. CNP-mediated generation of cGMP in RCS cells. (A) Cells (1x10⁵ per well) were treated with CNP for the indicated times and the intracellular cGMP concentration was determined by ELISA. The cGMP concentration in untreated cells was 0.023 pmol/well. The data represent the average from two wells. (B) Cells (1x10⁵ per well) were treated as indicated and the intracellular cGMP concentration was determined by ELISA. Note that the addition of fresh CNP failed to induce cGMP in cells previously treated with CNP. The data represent the average from two wells with the indicated range. (C) Cells (1x10⁵ per well) were pretreated with PDE inhibitors 30 minutes before treatment with CNP (5 hours) and the intracellular cGMP concentration was determined by ELISA. The data represent the average from two wells with the indicated range.