RESUMO
Objectives To investigate the effect of different dosages of low molecular weight heparin on acute pulmonary embolism and inhibition of pulmonary intimal hyperplasia in immature rats. Methods 90 male immature SD rats were randomly divided into ifve groups: sham group, pulmonary embolism group, low-low molecular heparin group (L-LMH), medium-low molecular heparin group (M-LMH) and high-low molecular heparin group (H-LMH). The model of acute pulmonary embolism was established through jugular vein injection with gel-foam solution. The rates in the L-LMH, M-LMH, H-LMH groups were treated with low molecular weight heparin by subcutaneous injection after surgery with a dosage of 0 . 005 ml/kg, 0 . 01 ml/kg, 0 . 02 ml/kg, twice a day. Animals in the control group were given saline injection. Arterial blood gas, pulmonary artery pressure (mPAP), right ventricular pressure (RVP), wall area/tube area, wall thickness/tube diameter, and the expression of PDGF-B and MCP-1 at gene and protein levels in lung tissue were detected on the 7 th ( 7 d), 14 th ( 14 d) and 28 th ( 28 d) after opration. Results There were signiifcant differences of PaO 2 among 5 groups on 7 d, 14 d and 28 d. PaO 2 in group M-LMH ( 105 . 1 ± 4 . 6 mm Hg) were signiifcantly higher than that of embolization group, L-LMH, but not H-LMH group at 28 d. mPAP of M-LMH group was lower than that in the other three intervention groups, but showed no signiifcant difference compared with sham group (P?>0 . 05 ). There were signiifcant differences of RVP on 7 d and 14 d. PDGF-B, MCP-1 of M-LMH group were signiifcantly lower compared with the other three intervention groups (P?0 . 05 ). Wall area/tube area, wall thickness/tube diameter scores of M-LMH group had no signiifcance differences compared with sham group on 28 d (P?>?0 . 05 ). Conclusion Medium dose of low molecular weight heparin could ameliorate the acute pulmonary embolism and inhibit the proliferation of pulmonary arteries in rats.