Fig. 1.

Effect of BPIPP on cGMP accumulation in cultured cells. (A) T84 cells were pretreated with 50 μM BPIPP or vehicle (0.1% DMSO) with or without 1 mM IBMX for 10 min and then treated with 0.1 μM STa (ST0.1) or 1 μM STa (ST1) for 10 min; intracellular (i) and extracellular (e) cGMP were assayed in the extract or in the treatment medium, respectively. n = 3–6. (B) Membranes were isolated from T84 cells and GC-C activity was assayed without stimulation (basal) or with 0.1 μM STa (STa 0.1), 1 μM STa (STa 1), or 3 mM MnCl₂ (Mn) in the presence of 50 μM BPIPP or vehicle. Similar data were obtained in membranes isolated in buffer containing protein phosphatase inhibitors from cells pretreated for 10 min with BPIPP. n = 3–4. (C) T84 cells were pretreated with 50 μM BPIPP or vehicle for 10 min and then with indicated concentrations of STa for 10 min, and cGMP accumulation was measured. n = 3. (D) T84 cells were pretreated with indicated concentrations of BPIPP or vehicle (Con) for 10 min and then with 0.5 μM guanylin or 100 nM STa for 10 min, and cGMP accumulation was measured. n = 6. (E) BE-2 cells were pretreated with indicated concentrations of BPIPP or vehicle (Con) for 10 min and then treated with 1 μM atrial natriuretic peptide (ANP) or 0.5 μM C-type natriuretic peptide (CNP) for 10 min, and intracellular cGMP was measured. n = 4. (F) RFL-6 cells were pretreated with 50 μM BPIPP or vehicle for 10 min and then with 10 μM nitric oxide donor benzotrifuroxan (NO donor), 1 μM ANP, or 1 μM CNP for 4 min. *, P < 0.01; n = 3.