Functional Role Of TRPV4 In Vascular Contraction In Hypertension

Cardiovascular disease is a serious threat to health, while hypertension is one of the most important and dangerous factors in cardiovascular disease. Endothelial dysfunction plays an important role in the development of hypertension. We found TRPV4-mediated contraction of vascular signaling pathway plays a key role in endothelial dysfunction, it is provided a new way for the development of drug targets.First, we used mice on a high-salt diet, L-NAME or AngII, and monitored their blood pressure every day. After activating the TRPV4（transient receptor potential vanilloid 4） receptor in the thoracic aorta, we measured changes in vascular tone by wire myograph and found that the TRPV4 channel mediated an abnormal contractile response in mice with high blood pressure.To further explore this phenomenon, we investigated thoracic aortic rings from mice with hypertension induced by a high-salt diet. When such rings were pretreated with RN-1734 or HC 067047（specific inhibitors of the TRPV4 channel）, we found that the abnormal contractile response was suppressed. By comparing intact and endothelium-denuded rings, we found that the abnormal contractions mediated by TRPV4 were endothelium-dependent. Using RT-PCR and Western blotting to assess the location and expression of COX-2 in the thoracic aorta, we found that COX-2 was mainly expressed in the endothelial cells and its expression was increased in hypertension. After incubating aortic rings from high-salt and control mice with COX-2-specific inhibitors（NS-398 and Celecoxib）, we measured the vascular tension. The results suggested that the contraction mediated by TRPV4 occurs via the COX-2 pathway. ELISA was used to detect the endothelium-derived contracting factor（EDCF） induced by activating the TRPV4 channels in thoracic aortic endothelial cells. The results indicated that this EDCF was PGF_2α, suggesting that TRPV4/COX-2 induces PGF_2α in the thoracic aorta in hypertension.In this study, we found that inhibiting the activity of Ca²⁺-sensitive cytosolic phospholipase A2（cPLA2） suppressed the abnormal thoracic aorta contractile response induced by the TRPV4 channel in hypertension. The interaction between TRPV4 and cPLA2 was assessed by immunofluorescent staining, which showed that TRPV4 co-localized with cPLA2 in amino–ethyl-carbazol tissue sections. To further investigate the coupling between TRPV4 and cPLA2, we used immuno-fluorescence resonance energy transfer to measure the spatial proximity between TRPV4 and cPLA2, and the results showed that a high-salt diet increased their physical coupling in primary vascular endothelial cells and in situ in the thoracic aortaIn summary, we demonstrated that the TRPV4 channel mediates the abnormal contractile response in the thoracic aorta of hypertensive mice via a TRPV4/Ca²⁺/COX-2/EDCF pathway. Inhibition of cPLA2 also reduced the TRPV4-mediated contractile response, and the physical coupling of TRPV4 to cPLA2 was enhanced in hypertension. This functional coupling deserves further study. This study provides a new means of studying vascular endothelial dysfunction in hypertension.