METRNL and hydrops fetalis: Adenovirus vectors containing either Src-shRNA or shMetrnl were intravenously injected into mice pre-HIIT respectively, in HF + HIIT + Src-shRNA and HF + HIIT + shMetrnl groups, while in HF + Metrnl group, intraperitoneal administration of exogenous Metrnl achieved Metrnl overexpression.