Effect of several pathway inhibitors on VEGF-induced cGMP production. BAEC were pretreated with IBMX (500 μM; 10 min), and with inhibitors or antagonists (up to 60 min) prior to VEGF stimulation in a DMEM/5 mM CaCl2 solution. cGMP production was detected by a RIA kit. Effect of VEGF (1 nM) on cGMP production upon a pretreatment with (A) eNOS inhibitor (L-NAME, 100 μM) or PLC pathway inhibitors (U73122, 10 μM; U73343, 10 μM; GF109203X, 5 μM; Ro318220, 1 μM or W-7, 250 μM). (B) cGMP synthesis upon stimulation with VEGF (1 nM) or A23187 (10 μM) on cGMP in a 5 mM CaCl2. Effect of VEGF (1 nM) on cGMP production upon a pretreatment with two chelators of calcium (EGTA/AM 100 μM or BAPTA/AM 10 μM) in a CaCl2-free solution. Effect of VEGF (1 nM) on cGMP production upon a pretreatment with (C) two PI3K inhibitors (Wortmannin, 500 nM or LY294002, 50 μM), (D) PAF mediator inhibitors (SB203580, 10 μM; PD98059, 10 μM or SB203347, 10 μM) or PAF receptor antagonists (BN52021 10 μM; LAU8080, 100 nM or CV3988, 1 μM). Effect of PAF (100 nM or 1 μM) on cGMP production. ***P<0.001 as compared to control buffer (PBS), †††P<0.001 as compared to VEGF (1 nM), *P<0.05 as compared to control buffer (PBS) in a DMEM CaCl2 free solution and †P<0.05 as compared to VEGF (1 nM) in a DMEM CaCl2 free solution.