Up-regulation of contractile endothelin receptors by airborne fine particulate matter in rat mesenteric arteries via activation of MAPK pathway.

Fine particle matters (PM2.5 ) is a well-known risk factor for cardiovascular diseases. However, the underlying molecular mechanisms are largely unknown. Vascular hyper-reactivity plays an important roles in the pathogenesis of cardiovascular diseases. The present study was designed to investigate a hypothesis that PM2.5 up-regulated endothelin receptors in mesenteric artery and the potential underlying mechanisms. Rat mesenteric arteries were cultured with PM2.5 . The artery contractile responses were recorded by a sensitive myograph. ETB and ETA receptor expressions of mRNA and protein were assessed by quantitative real-time PCR, Western blotting, and immunohistochemistry, respectively. Results showed that ETB receptor agonist, sarafotoxin 6c induced a negligible contraction in fresh artery segments, while ETA receptor agonist, ET-1 induced an obvious contraction. After organ culture, the contraction curve mediated by ETB and ETA receptors were shifted toward the left. PM2.5 1.0 μg/ml cultured for 16 h further enhanced ETB and ETA receptor-mediated contractile responses with a markedly increased maximal contraction. The organ culture enhanced ETB and ETA receptor mRNA and protein levels from fresh arteries, which were further increased by PM2.5 . The U0126 (MEK/ERK1/2 inhibitor) and SB203580 (p38 inhibitor) significantly attenuated both organ cultured-induced and PM2.5 -induced up-regulation of ETB receptor. U0126 also suppressed organ culture-increased and PM2.5 -increased expressions of ETA receptor. SB203580 only suppressed PM2.5 -induced enhanced expressions of ETA receptor In conclusion, airborne PM2.5 up-regulates ETB and ETA receptors of mesenteric artery via p38 MAPK and MEK/ERK1/2 MAPK pathways.