摘要Objective:To investigate whether cardiac mast cells(MCs)participate in pressure overload-induced myocardial hypertrophy through the regulation of transient receptor potential vanilloid 4(TRPV4).Methods:Pressure overload-induced myocardial hypertrophy was induced via abdominal aortic constriction(AAC).Myocardial hypertrophy was evaluated by measuring the heart weight index(HW/BW),lung weight index(LW/BW),ratio of heart weight to tibia length(HW/TL),ratio of lung weight to tibia length(LW/TL),and cross-sectional area of myocardial cells.qRT-PCR was used to detect the mRNA expression of TRPV4.Western blotting was used to detect the protein expression of TRPV4,mast cell tryptase,myosin heavy chain beta(β-MHC),calcineurin A(CnA),and nuclear factor of activated T-cell c3(NFATc3).ELISA was used to measure the levels of brain natriuretic peptide(BNP)and histamine.Fluo4 AM was used to detect the calcium signal in H9c2 myocardial cells.Results:Compared with those of the sham rats,the myocardial mast cells,tryptase,HW/BW,LW/BW,HW/TL,and LW/TL,the cross-sectional area of the myocardial cells,and the expression of β-MHC,TRPV4,CnA,and NFATc3 in the myocardial tissue and the serum BNP of the AAC-treated rats increased significantly,whereas the MC stabilizer cromolyn sodium(CS)reversed these indicators.In H9c2 cardiomyocytes,treatment with histamine and the TRPV4 agonist GSK1016790A upregulated the expression of TRPV4,β-MHC,BNP,CnA and NFATc3 and increased calcium ion influx,whereas these effects were inhibited by the H2 receptor inhibitor famotidine and the TRPV4 inhibitor HC067047.Conclusion:Cardiac MCs participate in pressure overload-induced myocardial hypertrophy through the upregulation of TRPV4 via its mediator histamine,and the Ca2+/CnA/NFATc3 signaling pathway is involved in this process.