Functional Improvement and Regression of Medial Hypertrophy in the Remodeled Pulmonary Artery after Correction of Systemic Left-to-Right Shunt

Figures

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  Figure 1. Measurement of cardiopulmonary morphometric function using the transthoracic echocardiography. Assessment of pulmonary artery (PA) diameter (A), PA pressure (B) and PA acceleration time (PAAT) measured at 4 weeks after fistula ligation (C). The peak flow velocity across pulmonary valve was significantly reduced at 4 weeks after aortocaval fistula ligation, and the diameter of PA was simultaneously reduced in corresponding to decrease in PA pressure. On the contrary, the PAAT increased significantly after ligation of aortocaval fistula, suggesting the reduction of pulmonary vascular resistance. Dotted lines indicate the levels of sham animals. Results were analyzed using unpaired t-test, and data are presented as mean ± SD. n = 6–8 different animals in each group. NL: non-ligation group; L: ligation group.

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  Figure 2. Measurement of cardiopulmonary morphometric function using the transthoracic echocardiography and RV/LV + S mass ratio. Assessment of right ventricular (RV) hypertrophy (A) and RV pressure (B). Ligation of aortocaval fistula at 2 and 4 weeks significantly reduced the tricuspid peak flow velocity, and the simultaneously attenuated the right ventricular hypertrophy measured by the RV/LV + S mass ratio. Dotted lines indicate the levels of sham animals. Results were analyzed using unpaired t-test, and data are presented as mean ± SD. n = 6–8 different animals in each group. *P < 0.05 compared with no ligation.

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  Figure 3. The overall cardiopulmonary changes related to the left ventricular (LV) function were assessed by the LV ejection fraction (A) and degree of pulmonary congestion (lung-wet-to-dry ratio, LWDR; (B). Results were analyzed using unpaired t-test, and data are presented as mean ± SD. n = 6–8 different animals in each group. *P < 0.05 compared with no ligation.

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  Figure 4. Measurements of isometric force of pulmonary artery in the sham-operated, and rats with flow-induced pulmonary hypertension. (A) Contraction responses of pulmonary artery to KCl (40 mM) and maximal concentration of phenylephrine (PE, 10−5 M). (B) Contraction responses of pulmonary artery to cumulative addition of phenylephrine (PE, 10−9 to 10−5 M). (C) Sensitivity of pulmonary contraction response to phenylephrine shown by % contraction. Results were analyzed using two-way RM ANOVA, and data are presented as mean ± SD. n = 6 different animals in each group. *P < 0.05 compared with AV fistula ligation.

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  Figure 5. Measurement of tissue concentrations of pro-inflammatory cytokines (IL-1β, IL-2, IL-6, IL-12, MCP-1 and TNF-α) in lung homogenates using the ELISA assay. *P < 0.05 compared with non-ligation group. n = 6–8 different animals in each group. Data were were analyzed using the Mann-Whitney U test and are shown as mean ± SD. Dotted lines denote the levels of sham-operated animals.

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  Figure 6. Representative blots of protein expressions of smooth muscle myosin heavy chain (SM-MHC)-II, α-smooth muscle actin (SMA), desmin and matrix metalloproteases (MMP)-2 in the isolated pulmonary artery of experimental rats. Ligation of aortocaval fistula restored the synthetic to contractile phenotyping of vascular smooth muscle cells by enhanced expressions of SM-MHC-II and α-SMA, and suppressed expression of desmin. *P < 0.05 compared with non-ligation group. n = 6 different animals in each group. Each band represents an independent tissue sample obtained from a different animal and the bands were visualized using an automated imaging system (UPV BioSpectrum) under the same experimental conditions. Data were analyzed by one-way ANOVA and are shown as mean ± SD.

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  Figure 7. Representative lung sections of animals with and without flow-induced pulmonary hypertension (A). Morphometric analysis of the medial thickness of the intralobular (ϕ 500–1000 μm, (B) and intraacinar (ϕ <250 μm, C) pulmonary artery. Thickness of medial layer is expressed as wall thickness to lumen radius (WT/LR) ratio (%). Thickness of medial layer was significantly reduced 4 weeks (lig 4w) after ligation of aortocaval fistula. *P < 0.05 compared with sham and †P < 0.05 compared with lig 4w. Magnifications are 100× for the upper panel and 200× for the lower panel. Analysis was performed in 5–6 different lung sections in each group, and the medical thickness was measured in at least 1 intralobular and 2 intraacinar pulmonary artery in each tissue section using the ImageJ software. Data were analyzed by one-way ANOVA and are shown as mean ± SD.