Effect of cyclic GMP-dependent vasodilators on the expression of inducible nitric oxide synthase in vascular smooth muscle cells: role of cyclic AMP

摘要

1. In the present study we examined whether interleukin-1β (IL-1β) increases the activity of adenylyl cyclase in vascular smooth muscle cells and determined its role in the cytokine-induced expression of the inducible nitric oxide synthase (iNOS) and activation of nuclear transcription factor-κB (NF-κB). In addition the interaction between cyclic AMP- and cyclic GMP-elevating agonists on the IL-1β-stimulated expression of iNOS was examined. 2. Exposure of vascular smooth muscle cells to IL-1β stimulated the formation of cyclic AMP but not of cyclic GMP. The intracellular level of cyclic AMP reached a maximum within 1 h and then gradually declined over the next 5 h. This IL-1β (60 u ml~(-1))-stimulated formation of cyclic AMP was modest (about 3 fold at 60 u ml~(-1) for 1 h) compared to that evoked by isoprenaline (about 9 fold at 3 x 10~(-6) M for 2 min). 3. The IL-1β (60 u ml~(-1) for 24 h)-stimulated accumulation of nitrite, which was taken as an index of NO production, was concentration-dependently increased by preferential inhibitors of cyclic AMP-dependent phosphodiesterases (rolipram and trequinsin). This effect was reproduced by a specific activator of the cyclic AMP-dependent protein kinase(s) A, Sp-8-CPT-cAMPS (10~(-4) M) but was prevented by a specific inhibitor of cyclic AMP-dependent protein kinase(s) A, Rp-8-CPT-cAMPS (10~(-4) M). These compounds alone [rolipram (10~(-6) M), trequinsin (3 x 10~(-6) M) and Sp-8-CPT-cAMPS (10~(-4) M)] slightly but significantly increased the release of nitric oxide while Rp-8-CPT-cAMPS elicited no such effect.