Stimulation of the EP 3 receptor causes lung edema by activation of TRPC6 in pulmonary endothelial cells

Prostaglandin E (PGE ) increases pulmonary vascular permeability by activation of the PGE receptor 3 (EP ) which may explain adverse pulmonary effects of the EP /EP receptor agonist sulprostone in patients. PGE also contributes to pulmonary edema in response to platelet-activating factor (PAF). PAF increases endothelial permeability by recruiting the cation channel transient receptor potential canonical 6 (TRPC6) to endothelial caveolae acid sphingomyelinase (ASMase). Yet, the roles of PGE and EP in this pathway are unknown. We hypothesized that EP receptor activation may increase pulmonary vascular permeability by activation of TRPC6, and thus, synergize with ASMase-mediated TRPC6 recruitment in PAF-induced lung edema. In isolated lungs, we measured increases in endothelial Ca (ΔCa ) or lung weight (Δweight), and endothelial caveolar TRPC6 abundance as well as phosphorylation. PAF-induced ΔCa and Δweight were attenuated in EP -deficient mice. Sulprostone replicated PAF-induced ΔCa and Δweight which were blocked by pharmacologic/genetic inhibition of TRPC6, ASMase, or Src-family kinases (SrcFK). PAF, yet not sulprostone, increased TRPC6 abundance in endothelial caveolae. Immunoprecipitation revealed PAF- and sulprostone-induced tyrosine-phosphorylation of TRPC6 that was prevented by inhibition of phospholipase C (PLC) or SrcFK. PLC inhibition also blocked sulprostone-induced ΔCa and Δweight, as did inhibition of SrcFK or G signaling. EP activation triggers pulmonary edema G -dependent activation of PLC and subsequent SrcFK-dependent tyrosine phosphorylation of TRPC6. In PAF-induced lung edema this TRPC6 activation coincides with ASMase-dependent caveolar recruitment of TRPC6, resulting in rapid endothelial Ca influx and barrier failure.