Role of notch signal in angiotensin II induced pulmonary vascular remodeling.

OBJECTIVE: Notch signal is particularly important to vascular remodeling during the process of embryonic development, vessel repair and tumor growth, but there are few studies about pulmonary vascular remodeling in pulmonary hypertension. This study was to explore the effect of inhibiting Notch signal on pulmonary vascular remodeling induced by angiotensin II. METHODS: Vessel strips taken from healthy Wistar rats were cocultured with extrogenous angiotensin II and the potent smooth muscle cell proliferation stimulators for 7 days. Vascular wall thickness, proliferating cell nuclear antigen (PCNA) positive cell rate, and caspase-3 positive cell rate were examined in vessel strips. Some of the vessel strips were cultured with angiotensin II and γ-secretase inhibitor DAPT, a Notch signaling inhibitor, for 7 days. The levels of Notch 1 to 4 receptor and HERP1/2 mRNA were ascertained by FQ-PCR. RESULTS: Angiotensin II stimulation in the cultured normal pulmonary arteries resulted in an increase in the vascular medial thickness by nearly 50%, and a significant increase in the PCNA positive cell rate and a decrease in the caspase-3 positive cell rate (P<0.05). DAPT treatment did not alter the levels of Notch 1 to 4 receptor but remarkably decreased HERP1 and HERP2 mRNA expression (P<0.05). DAPT treatment also decreased angiotensin II-induced vascular medial thickness and PCNA positive cell rate, and increased caspase-3 positive cell rate (P<0.05). CONCLUSIONS: Inhibition of Notch signal by the γ-secretase inhibitor may suppress pulmonary vascular remodeling induced by angiotensin II, suggesting that the inhibition of Notch signal pathway might be a novel strategy for the treatment of pulmonary hypertension.

[Effect of inhibition of Notch signal on pulmonary vascular remodeling induced by angiotensin â ¡].

OBJECTIVE: It is known that Notch signal is very important to vascular remodeling during the process of embryonic development, vessel repair and tumor growth, but there are few studies about pulmonary vascular remodeling in pulmonary hypertension. This study was to explore the effect of inhibiting Notch signal on pulmonary vascular remodeling induced by angiotensin II. METHODS: Vessel strips taken from healthy Wistar rats were co-cultured with extrogenous angiotensin II and the potent smooth muscle cell proliferation stimulators for 7 days. Vascular wall thickness, proliferating cell nuclear antigen (PCNA) positive cell rate and caspase-3 positive cell rate were examined in vessel strips. Then some vessel strips were cultured with angiotensin II and γ-secretase inhibitor DAPT, a Notch signaling inhibitor for 7 days. The levels of Notch 1 to 4 receptor and HERP1/2 mRNA were ascertained by FQ-PCR. RESULTS: Angiotensin II stimulation in the cultured normal pulmonary arteries resulted in an increase in the vascular medial thickness by nearly 50%, and a significant increase in the PCNA positive cell rate and a decrease in the caspase-3 positive cell rate. DAPT treatment did not result in the alterations of Notch 1 to 4 receptor levels, but decreased remarkably HERP1 and HERP2 mRNA expression. DAPT treatment also decreased angiotensin II-induced vascular medial thickness and PCNA positive cell rate and increased caspase-3 positive cell rate. CONCLUSIONS: Inhibiting Notch signal by γ-secretase inhibitor may lead to the suppression of pulmonary vascular remodeling induced by angiotensin II, suggesting that the inhibition of Notch signal pathway might be a novel strategy for the treatment of pulmonary hypertension.

[The influence of inhibiting notch signal on pulmonary vascular remodeling induced by PDGF].

OBJECTIVE: To explore the influence of inhibiting Notch signal on pulmonary vascular remodeling induced by PDGF. METHODS: Vessel strips taken from healthy Wistar rats were cultured together with extrogenous PDGF, the potent smooth muscle cell proliferation stimulators, for 7 days. Some vessel strips were cultured with PDGF and gamma-secretase inhibitor DAPT, a Notch signaling inhibitor for 7 days. Vascular wall thickness, PCNA and caspase-3 positive cell rate were examined in vessel strips. The alterations of Notch 1 to 4 receptor and HERP1, 2 mRNA were discerned by FQ-PCR to observe the influence of DAPT on Notch signal. At the same time, above indexes, which were related with pulmonary vascular remodeling, were measured too. RESULTS: PDGF stimulation in the cultured normal pulmonary arteries resulted in vascular medial thickness increase for about 50%, accompanied by significant increase in PCNA positive cell rate and decrease of caspase-3 positive cell rate. When DAPT were added to inhibit Notch signaling, the expression of HERP1, 2 mRNA decreased, the degrees of PDGF induced vascular medial thickness and PCNA positive cell rate increase as well as caspase-3 positive cell rate decrease were all attenuated notably. CONCLUSION: Inhibiting Notch signal induced by gamma-secretase inhibitor lead to the suppression of pulmonary vascular remodeling induced by PDGF, suggesting inhibition of Notch signal pathway might be a novel strategy in the intervention of pulmonary hypertension.

[Effects of simvastatin on proliferation and transition of phenotype in PDGF-BB-induced pulmonary artery smooth muscle cells].

OBJECTIVE: To investigate the effects of simvastatin on inhibiting cell phenotype and potential mechanism in PASMC induced by PDGF-BB. METHODS: PASMC isolated from SD rats and cultured in vitro were induced by PDGF-BB and then intervened by simvastatin and Y-27632. Flow cytometry were performed to detect cell proliferation. Fluorescence quantitative RT-PCR was performed to detect alpha-SM-actin mRNA expression and Western blot was applied to detect the expression of alpha-SM-actin, SM22alpha and RhoA protein. RESULTS: Simvastatin and Y-27632 obviously increased the level of mRNA of alpha-SM-actin and promoted the protein expression of alpha-SM-actin, SM22alpha while inhibiting the proliferation of PASMC induced by PDGF-BB. Simultaneously, inhibited expression of RhoA induced by simvastatin and Y-27632 was also observed. CONCLUSION: The inhibited effect of simvastatin on the proliferation of PASMC induced by PDGF-BB may be achieved by inhibiting conversion of cell phenotype. And the potential mechanism may through the RhoA/Rho kinase signaling pathway.

Simvastatin restores down-regulated GATA-6 expression in pulmonary hypertensive rats.

Vascular smooth muscle cell proliferation has been known to be predominant in vascular remodeling of pulmonary hypertensive. The GATA family proteins, a group of zinc finger transcription factors, play an important role during cell proliferation. The aim of present study was to investigate the expression of GATA-6 gene in experimental pulmonary hypertensive rats and explore the effect of regulation of GATA-6 expression by simvastatin on pulmonary vascular remodeling. The male Sprague-Dawley rats model was established with receiving pneumonectomy and monocrotaline (MCT) administration. Right pulmonary artery remodeling in these animals was compared with untreated rats or rats receiving simvastatin. The level of GATA-6 mRNA and protein expression was detected by reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blotting, respectively. Pneumonectomized, MCT-treated rats had significantly increased mean pulmonary arterial pressure (mPAP), RV/(LV + S) ratio (ratio of the right ventricular to left ventricular and septum weights), vascular occlusion scores (VOSs), and percent media wall thickness on day 35, all the indices were significantly decreased after simvastatin administration in these rats. The level of GATA-6 mRNA and protein were markedly decreased in these pneumonectomy and MCT-treated rats, and they were significantly up-regulated in these rats after receiving simvastatin. These results indicate that the development and progression of pulmonary hypertension is prevented by simvastatin by up-regulating GATA-6 expression in the lung tissue.

[Effect of polycythemia on hypoxia induced pulmonary hypertension and pulmonary vascular remodeling in rats].

OBJECTIVE: To investigate the effect of polycythemia on hypoxia induced pulmonary hypertension and pulmonary vascular remodeling in rats. METHODS: The healthy female Sprague-Dawley rats were randomly divided into 3 groups: normoxia control group (C group), hypoxia group (H group), hypoxia + different doses of human recombine hemopoietin (rEPO) group. All rats in hyoxia groups were exposed to hypoxia, 8 hours every day, for 21 days. The rEPO groups were injected sc with different doses of rEPO (300 U/kg, 600 U/kg, 900 U/kg, 1200 U/kg) thrice weekly. Blood samples were taken for the measurement of RBC, Hb, Hct, plasma EPO concentration, whole blood/plasma viscosities, the animals were then catheterized to record mean pulmonary arterial pressure (mPAP) and demised to calculate the ratio [RV/(LV+S)]. Percentage of vascular wall thickness and muscularization of non-muscular pulmonary arteriole were examined microscopically. RESULTS: (1) As the dosage of exogenous rEPO increased, blood concentration of EPO increased correspondingly, as RBC, Hb, Hct and whole blood/plasma viscosities increased in various degrees. (2) There was positive correlation between whole blood viscosity and Hct at both high and low shears and linear correlation between mPAP and whole blood viscosity at high shear. (3) The degree of pulmonary hypertension, reflected by mPAP increased in accordance to rEPO dosage increment. However, the extent of pulmonary vascular remodeling alleviated somehow as the rEPO dose increased and so did right ventricular hypertrophy. CONCLUSION: Polycythemia induced by exogenous EPO increases the blood viscosity and the pulmonary vascular resistance, which contributes to the formation of hypoxia induced pulmonary hypertension.

[Effect of doxycycline on the development of pulmonary hypertension induced by four methods in rats].

OBJECTIVE: Based on establishment of four rat models of experimental pulmonary hypertension (PH), the authors examined the inhibition of matrix metalloproteinases (MMPs) by doxycycline and its effect on the development of PH and associated pulmonary vascular remodeling. METHOD: Healthy male Sprague-Dawley rats (weight 350 g to 400 g) were randomly divided into nine groups: Normal control group (N), four model groups (H, M, P, PM) and their corresponding drug intervention groups (HD, MD, PD, PMD) in which doxycycline was given by gavage at a 20 mg/kg daily dosage. On day 28 (day 35 for PM and PMD models), the animals were catheterized to record mean pulmonary arterial pressure (mPAP) and then sacrificed. Fulton Index [RV/(LV + S)] was measured immediately. Morphometric parameters, including percent vascular wall thickness and muscularization of non-muscularized peripheral pulmonary arterioles were determined microscopically. The activity of MMPs was measured by gelatin zymography in the lung tissue. RESULTS: (1) Rats in all model groups (H, M, P, PM) developed significant pulmonary arterial hypertension and right ventricular hypertrophy in comparison with their corresponding drug intervention groups (HD, MD, PD, PMD) and normal control group (N) (P < 0.01). For example, mPAP (mm Hg)(1 mm Hg = 0.133 kPa):N: 18.10 +/- 1.45, H: 27.20 +/- 1.55, HD: 23.90 +/- 2.13; Fulton Inedx(%):N: 23.41 +/- 1.84, H: 34.44 +/- 2.70, HD: 27.55 +/- 2.45. (2) The percent vascular wall thickness (WT%) and percentage of muscularization of non-muscular pulmonary arterioles were significantly increased in all model groups compared with drug intervention groups and normal group (P < 0.01). For example, WT%:N: 10.90 +/- 3.11, H:41.41 +/- 5.21, HD: 17.73 +/- 3.12; Muscularization(%):N: 13.83 +/- 3.72, H: 44.93 +/- 2.43, HD: 29.89 +/- 4.45. (3) The activity of MMPs was inhibited by doxycycline effectively as assessed by gelatin zymography (P < 0.01). For example, the activity of MMP2 (A x 10(3)):N: 1.43 +/- 0.24, H: 3.58 +/- 0.28, HD: 2.29 +/- 0.31. CONCLUSION: Doxycycline attenuated PH and associated pulmonary vascular remodeling in all rat PH models. The study suggests that high expression and enhanced activity of MMPs may play a brutial role in the development of PH. Such phenomenon seems to be common in a variety of PH models of different etiology.

[Changes of MMP-2,9 and TIMP-1 expressions in rats with pulmonary arterial hypertension after captopril and losartan interventions].

OBJECTIVE: To determine the effect of captopril and losartan on the expressions of matrix metalloproteinase-2,9 (MMP-2,9) and metalloproteinase-1 (TIMP-1) in rats with pulmonary arterial hypertension, and the mechanisms of captopril and losartan in intervening the development of pulmonary arterial hypertension. METHODS: Forty male Spraque-Dawley rats were divided into 4 groups randomly: pulmonary arterial hypertension (created by pneumonectomy plus MCT injection) model group (PAH Model), PAH model treated with captopril [PAH+Cap 10 mg/(kg x d)], losartan group [PAH+Los 15 mg/(kg x d)] and normal control group(Control). The mPAP, weight ratio of RV to LV+S, neointima formation, relative thickness of small pulmonary arteries, and degree of muscularization of non-muscular arterioles were measured at day 35. The expression of SM-a-actin in the PASMC was determined by immunochemistry stain. The expressions of MMP-2, 9, TIMP-1 and MMP-2, 9, TIMP-1 mRNA in the pulmonary tissues were determined by immunohistochemistry and FQ-PCR respectively. The enzymatic activity of MMP-2, 9 was measured by Gelatin zymography. RESULTS: Pneumonectomy plus MCT injection induced severe pulmonary arterial hypertension characterized by neointimal formation. Captopril or losartan suppressed the increase of mPAP, right ventricle weight, thickness of small pulmonary arteries and muscularization of peripheral pulmonary arterioles in the rats with PAH (P < 0.05). The PAH model group had higher expressions of MMP-2, 9, TIMP-1 mRNA and enzymatic activity of MMP-2, 9 in lung tissue than the other groups (P < 0.05). Captopril intervention had similar effects as losartan intervention. CONCLUSION: The captopril and losartan induced attenuation of PAH and pulmonary vascular remodeling is likely to be associated with the regulation of the expressions of MMP-2, 9, TIMP-1.

[Expression of connective tissue growth factor and its down-regulation by simvastatin administration in pulmonary hypertensive rats].

OBJECTIVE: To explore the role of expression of connective tissue growth factor (CTGF) in pulmonary vascular remodeling of pulmonary hypertensive rats, and investigate the regulation of CTGF expression by simvastatin in this animal model. METHODS: Eighty male Sprague-Dawley rats (350 to 400 g) were randomized to 7 groups. The rats in group PM(1 - 21) (n = 10) and PM(1 - 35) (n = 12) were treated with pneumonectomy + monocrotaline (MCT), and sacrificed at the 21st or 35th experimental day;those in groups PMS(1 - 35) (n = 12), PMS(21 - 35) (n = 12), PMV(1 - 35) (n = 12) and PMV(21 - 35) (n = 12) were given daily lavage of simvastatin (or vehicle) as intervention measure which began from the 1st and 21st experimental days, respectively; additional 10 rats were used as control without any intervention. The animals were sacrificed at the end of experiment (35 th day) as hemodynamic measurements and study on the morphological parameters relevant to pulmonary vascular remodeling were performed on each group of rats. The expression of ET-1 mRNA, CTGF mRNA and protein, and synthesis of collagen in these pneumonectomized, MCT-treated rats were compared between control and rats treated with simvastatin. RESULTS: Rats in PM(1 - 35) Group developed severe PAH (mPAP = 39.75 +/- 3.62 mm Hg) (1 mm Hg = 0.133 kPa), right ventricular hypertrophy [RV/(LV + S) ratio = 0.627 +/- 0.040], and arterial medial hypertrophy (WT% = 61.73 +/- 5.39), these parameters of the control animals were 17.10 +/- 1.20 mm Hg, 0.262 +/- 0.018 and 14.71 +/- 1.16, respectively. CTGF mRNA and protein were mainly located in pulmonary arterial smooth muscle cells and interstitial macrophage shown by in situ hybridization and immunohistochemistry, respectively. The expression of ET-1 mRNA and CTGF mRNA detected by fluorescent quantitative RT-PCR in Group PM(1 - 35) were significantly increased in comparison with controls, and so did the CTGF protein expression determined by Western blotting in these diseased rats. The content of hydroxyproline (1.30 +/- 0.19 microg/mg wet lung) was remarkably higher than that of control animals (0.56 +/- 0.10 microg/mg wet lung). The up-regulation of ET-1 and CTGF gene expression, and elevated synthesis of hydroxyproline were reversed in rats intervened with simvastatin. The pulmonary hypertension, right ventricular hypertrophy and medial hypertrophy were attenuated in all simvastatin-treated rats no matter the intervention was initiated from the beginning or midway of the study. CONCLUSION: The up-regulation of CTGF gene expression may play an important role in the development of pulmonary vascular remodeling in PAH. Simvastatin can prevent and, to some extent, reverse the vascular remodeling via down-regulation of CTGF gene expression.

[Effect of triptolide on the development of monocrotaline-induced pulmonary hypertension in pneumonectomized rat].

OBJECTIVE: To investigate the effect of Triptolide on the development of monocrotaline(MCT)-induced pulmonary hypertension and right ventricular hypertrophy in pneumonectomized rat. METHODS: Sixty male Sprague-Dawley rats were randomly divided into continuous Triptolide therapy group, delayed Triptolide therapy group, two placebo groups, model group and normal group, of which the mean pulmonary arterial pressure (mPAP), right ventricular index (RV/LV+S) were observed or checked. The light microscope, image analysis and immunohistochemistry were used to show percent vascular wall thickness (WT%), the degree of muscularization and vascular occlusion score in pulmonary arteries. RESULTS: (1) Each index of model group was obviously increased (P < 0.01 vs. common group). (2) The indexes of two therapy groups were attenuated for the pneumonectomized rats that suffered from MCT induced pulmonary hypertension (P < 0.05 vs. model group and placebo group). (3) There was the statistics significance between the two therapy groups in all indexes except for the degree of muscularization (P < 0.05). CONCLUSION: For pneumonectomized rats that suffer from the MCT pulmonary hypertension and undergo the pulmonary vascular remodeling, triptolide can slow down pulmonary hypertension, right ventricular bypertrophy and promote the regression of pulmonary arterial neointimal formation before and after forming pulmonary hypertension.

[Effect of triptolide on the expression of matrix metalloproteinases 2 and 9 in lungs of experimental pulmonary hypertension].

OBJECTIVE: It has been shown that triptolide can attenuate pulmonary arterial hypertension in rats. This study was designed to investigate the therapeutic effect of triptolide on pulmonary hypertension in rats and possible mechanisms. METHODS: Sixty Sprague-Dawley (SD) rats were randomly divided into 6 groups: normal control, model, continuous triptolide-treated, delayed triptolide-treated and two placebo groups for continuous and delayed fashions (n=10 each). The rats from the last 5 groups were injected with monocrotaline (MCT, 60 mg/kg) on day 7 after left pneumonectomy. The rats in the continuous triptolide-treated group received therapy from day 5 to 35 with triptolide (0.25 mg/kg intraperitoneally, every other day) and those in the delayed triptolide-treated received therapy with triptolide (0.20 mg/kg intraperitoneally, daily) from day 21 to 35 after operation. The hemodynamic parameters were detected by catheterization and the pathologic changes of small pulmonary arteries were evaluated by light microscopy 5 weeks post-operation. The expression of matrix metalloproteinases (MMPs) was assessed by immunohistochemistry and quantitative fluorescence PCR of relevant (MMP2 and MMP9) mRNAs. RESULTS: By day 35 after operation, the mean pulmonary arterial pressure (mPAP, 38.10+/-1.20 vs 16.70+/-1.16 mmHg)the ratio of right ventricle/left ventricle plus septum [RV/(LV+S), 62.45+/-5.28% vs 22.76 +/-3.01%] and the vessel obstructive scores (VOS, 1.736 +/-0.080 vs 0.000 +/-0.000) increased significantly in the Model group compared with those of the normal control group (P < 0.01). The expression of MMP2 and MMP9 and their mRNA expression in lung tissues obviously also elevated in the Model group (P < 0.05). The continuous and the delayed triptolide-treated groups had significantly lower mPAP (20.80+/-1.03 and 26.20+/-1.03 mmHg, respectively) and less right ventricular hypertrophy and pulmonary arterial neointimal formation compared with the model and the placebo groups. The two treated groups also demonstrated decreased expression of MMP2 and MMP9 and their mRNA expression in lung tissues. There were significant differences in mPAP, RV/(LV+S) and VOS between the two triptolide-treated groups. CONCLUSIONS: Triptolide attenuates the development of pulmonary hypertention and right ventricular hypertrophy and promotes regression of pulmonary arterial neointimal formation in pneumonectomized rats that received MCT, possibly through an inhibition of MMPs activity.

[Effect of simvastatin on rat pulmonary hypertension induced by high pulmonary blood flow and injected monocrotaline].

OBJECTIVE: To explore the therapeutic effect of simvastatin on the pulmonary hypertension induced by injected monocrotaline combining with high pulmonary blood flow of rats. METHODS: Forty male SD rats were randomly divided into the placebo group, simvastatin 1 mg/(kg x d) group, simvastatin 2 mg/(kg x d) group and control group. The arterial-venous shunt rats were injected with monocrotaline at day 7 and developing the pulmonary hypertension after shunting operation. Rats were received either placebo or treatment with simvastatin in the respective group. On day 37 after the shunt operation, the mean pulmonary artery pressure (mPAP) and right ventricular hypertrophy Cright ventricle/(left ventricle+septum), RV/(LV+S)) of all rats were measured. The percent vascular wall thickness and muscularization of the pulmonary small arteries were evaluated. The blood samples were collected to compare the total cholesterol levels between groups. RESULTS: The RV/ (LV+S) and mPAP elevated obviously in placebo group compared to the control group (P<0. 05). The muscularization of pulmonary small arteries and pulmonary artery medial hypertrophy increased significantly in placebo group compared with the control group (P<0. 05). The simvastatin treatment made the attenuation of the above-mentioned indexes in this animal model (P<0. 05). There was no significant statistics difference of the total cholesterol levels between any two groups (P > 0. 05). CONCLUSION: By inhibiting the pulmonary vascular remodeling, simvastatin attenuated the development of pulmonary hypertension. Simvastatin may have preventive and therapeutic effects on pulmonary hypertension.

[Interventional approach to the treatment of aneurysms of the perimembranous ventricular septal defects].

OBJECTIVES: To explore applicable protocol for the positioning of ventricular septal defect (VSD) occluder and the selection of the device by retrospective analysis of transcatheter closure approach to the aneurysms of the perimembranous VSD. METHODS: Thirty-five cases of perimembranous VSD with septal aneurysm (19 males and 16 females) from May, 2004 to May, 2005 were included, with a mean age of 5.3 y and mean weight of 17.6 kg. Their angiographic and ultrasound data, and interventional processes were analyzed. Seven segments of the aneurysms were assessed: the diameter of the defect on the left ventricle, the diameter of the defect on the right ventricle, the thickness of ventricular septum, the distance from the farthest end of the aneurysm to the defect, the diameter of the widest part of the aneurysm and the distance between the two farthest orifices on the aneurysm. RESULTS: Sixteen cystiform aneurysms and nineteen tubiform ones were identified with left ventricular angiography. The diameters of the orifices of aneurysms and the diameters of the VSDs ranged from 1.5 mm to 4.1 mm and 2.7 mm to 11.9 mm, separately, with the mean of 2.9 mm and 4.3 mm. From the echocardiography, the distances of the rim of defect to the aortic valve ranged from 2.0 mm to 7.0 mm, with the mean of 4.3 mm. All the interventions were successfully done with symmetrical devices from 4 mm to 14 mm. The left disc of the device was positioned at the defect surface from the left ventricle in 29 cases, and was released at the left side of the orifice in 3 cases. CONCLUSIONS: The positioning of the left disc is mostly determined by the condition for the correct formation of the right disc in the right ventricle after deploying. Generally the defect surface in the left ventricle is most ideal to release the left disc of the device. If the body of aneurysm was too long for the right disc to restore its configuration, the left disc should be released on the left side of the orifice. The selection of device size is determined by the placement of the left disc. When the left disc is to be released at the defect surface in the left ventricle, the device size should be equal to or 1 to 2 mm larger than the diameter of the defect on the left ventricle. When the left disc is to be deployed on the left side of an orifice, the device size should be equal to or 1 mm larger than the defect diameter on the left ventricle when there is a single orifice. In the case of multiple orifices, the minimal size of the device which can cover all the orifices should be selected.

[The change of mast cells and macrophages in the lung of rat with pulmonary hypertension].

OBJECTIVE: To investigate the change of mast cells and macrophages in lung tissue of rats with pulmonary hypertension (PH) and the effect of simvastatin on it. METHODS: Pulmonary hypertension was established as follow, a shunt between abdominal aorta and inferior vena cava was created in rats, 8 days later, the rats were injected with monocrotaline (60 mg/kg). Moreover, a subgroup of rats were given simvastatin 2 mg/ (kg x d). The mean pulmonary artery pressure (mPAP) and right ventricular weight were measured, and the ratio of right ventricle/left ventricle plus septum CRV/(LV+S)) was calculated. The LSAB method was used to stain anti-tryptase and ED1 in the lung tissue of the rats. RESULTS: In comparision with the control group, mPAP and RV/ (LV+S) of PH rats increased significantly (P<0.05). The RV/(LV+S) in simvastatin group was lower than that in PH rats (P<0.05). The amount of mast cells and macrophages in PH rats were more than that in control group (P<0.05). The amount of mast cells in simvastatin intervention group decreased in comparision with the PH group while the macrophages showed no difference in simvastatin group (P>0.05). CONCLUSION: Mast cells and macrophages may be involved in the development of PH and/or the lesion caused by PH accelerate the accumulation and activation of mast cell and macrophages. Simvastatin has a preventive effect on rat PH, it inhibits mast cell proliferation may be one of mechanism.

[Effect of captopril on pulmonary vascular remodeling induced by left-to-right shunt in rats].

OBJECTIVE: To investigate the therapeutic effect of angiotensin converting enzyme inhibitor on pulmonary vascular remodeling of pulmonary hypertension induced by high pulmonary blood flow. METHODS: An arterial-venous shunt was surgically created between abdominal aorta and inferior vena cava in the rat of all groups except the control group. Captopril was given to all of the rats. Six weeks after the operation,pulmonary artery systolic pressure (PASP), pulmonary artery diastolic pressure (PADP) and right ventricular systolic pressure (RVSP) were measured. The rats' hearts were weighted to calculate the ratio of right ventricle mass to left ventricle plus septum mass. Immunohistochemical stains were used to identify alpha-actin and PCNA distribution in pulmonary arteries. Morphometric parameters (vascular wall thickness and muscularization) were used to assess the remodeling of small pulmonary arteries. RESULTS: The PASP, PADP, RVSP, RV/(LV+S), RV/BW, and (LV + S)/BW of the rats in the shunt group were significantly greater than those of the control group. Muscularization of small pulmonary arteries and pulmonary artery medial hypertrophy (wall thickness) were evident in the shunt group. The proliferation index of the smooth muscle cells of the small and medium-sized pulmonary arteries was significantly higher and the alpha-actin IOD was significantly lower in the rats of the shunt group than those of the control. By contrast, the levels of PASP, PADP, RVSP, RV/(LV+S), RV/BW, (LV+ S)/BW, and muscularization were lower in the rats of captopril group than those of the control. CONCLUSIONS: Captopril slows down pulmonary hypertension and remodeling development. Captopril and losartan may have preventive and therapeutic effects on pulmonary hypertension induced by congenital left-to-right shunts.

[Differences of Angiotensin II receptor expression between systemic and pulmonary circulation in children with left-to-right shunt congenital cardiac lesions].

OBJECTIVE: It has been shown that angiotensin converting enzyme inhibitors (ACEI) can reduce the ratio of pulmonary and systemic circulation blood flow (Qp/Qs) and thus decrease the blood flow of left-to-right shunt in children with left-to-right shunt congenital cardiac lesions. This suggests that there are differences in the expression of Angiotensin II receptors between systemic and pulmonary circulation. This study aimed to explore the differences of Angiotensin II receptors type 1 and type 2 (AT1 and AT2 receptors) expression between systemic and pulmonary circulation in children with left-to-right shunt congenital cardiac lesions. METHODS: Lung and skeletal muscular tissues were obtained from 20 children with left-to-right shunt congenital cardiac lesions by biopsy during operation. The specimens were stained by immunohistochemistry techniques for AT1 and AT2 receptors. The technique of morphometric analysis was used to measure the immunoreactivity of AT1 and AT2 receptors (expressed by IOD values) of pulmonary, skeletal muscular and pleural small vascular wall the diameter of which was 15-100 microm. RESULTS: The immunoreactivities of AT1 and AT2 receptors of pulmonary small vascular walls [(124 +/- 95)x10(3) and (85 +/- 62)x10(3) respectively] were significantly lower than those of skeletal muscular [(219 +/- 156)x10(3) and (155 +/- 139)x10(3) respectively] and those of pleural small vascular walls [(279 +/- 191)x10(3) and (175 +/- 128)x10(3) respectively] in children with left-to-right shunt congenital cardiac lesions (P < 0.05). CONCLUSIONS: The expression of AT1 and AT2 receptors in small vascular walls of systemic circulation was higher than that of pulmonary circulation in children with left-to-right shunt congenital cardiac lesions.

[Expression of GATA6 gene in lung tissue of rat with pulmonary hypertension].

OBJECTIVE: To investigate the expression of GATA6 gene in lung tissue of rat with pulmonary hypertension. METHODS: Male Sprague-Dawley rats (350 to 400 g) were received monocrotaline (MCT) (60 mg/ kg) subcutaneous injection on day 7 after left lung resection. Mean pulmonary artery pressure (mPAP), right ventricle (RV) / [left ventricle (LV)+ interventricular septum (S)] ratio and pulmonary artery wall thickness (WT%) were detected on day 1, 21, 35 after left lung resection, respectively. Neointimal formation in small pulmonary vessels was observed by Von Gienson stain. The level of expression of GATA6 mRNA in lung tissue was detected by reverse transcription polymerase chain reaction (RT-PCR). RESULTS: Neointimal changes developed in right lung intra-acinar vessels on day 35 after left lung resection (day 28 after MCT injection). Neointimal lesions did not develop in control animals. Animals treated with left lung resection plus MCT had significantly increased mPAP values on day 21 [(27.10 +/- 2.02) mmHg, 1 mmHg = 133.32 Pa], with a further increase on day 35 (39.75 +/- 3.62) mmHg, as compared with control animals [(16.80 +/- 1.03) mmHg, day 21; (17.10 +/- 1.20) mmHg, day 35, P < 0.0001]. The RV/(LV+S) ratio increased from 0.266 +/- 0.015 (day 1) to 0.456 +/- 0.025 (day 21) and 0.627 +/- 0.040 (day 35), as compared with those of control animals (P < 0.0001) (0.267 +/- 0.016 (day 1), 0.272 +/- 0.015 (day 21) and 0.257 +/- 0.019 (day 35)]; Compared with normal pulmonary arteries, MCT injection after left lung resection resulted in severe media hypertrophy after 35 days. The level of GATA6 mRNA in rats received left lung resection plus MCT was downregulated about 4-fold on day 35, compared with that in control animals, and these tendency was observed on day 21 after left lung resection. CONCLUSION: The expression of GATA6 gene is downregulated in neointimal model of pulmonary hypertension, it suggests that GATA6 may play a key role in pulmonary vascular remodeling.

[Effects of Losartan on expression of heme oxygenases in volume-overloaded rats with left-to-right shunt].

OBJECTIVE: To study the expression of heme oxygenase-1 mRNA and pulmonary remodeling before and after surgical establishment of left-to-right shunt in volume-overloaded SD rats and rats with Losartan intervention. METHODS: Left-to-right shunt volume-overloaded SD rat models were established by aortocaval shunt operation. Seven rats with shunt were placed on Losartan (Losartan group), 7 rats with but not given Losartan were included in the operation group, and 4 rats after sham operation served as controls. Pulmonary pressure and right ventricular pressure were measured during catheterization. The relative weights ventricles were determined after execution of the rats. Pulmonary vascular remodeling parameters, including percentage arterial wall thickness and percentage muscularized small arteries, were assessed by morphometry. Heme oxygenase-1 (HO-1) mRNA expression and heme oxygenase-2 (HO-2) mRNA expression were detected RT-PCR method. RESULTS: Pulmonary artery pressure and right ventricular relative weight decreased significantly in the rats of Losartan group; in addition, the percentage arterial wall thickness and percentage of muscularized small arteries in the Losartan group were reduced as compared with those in the operation group. The level 1 mRAN expression in rats with shunt was significantly higher than that in rats without shunt. The level mRNA expression in the Losartan group decreased remarkably as compared against that in the operation The level of HO-1 mRNA expression in lungs was significantly higher than that in ventricles. There statistically significant differences in HO-2 mRNA expression levels between the three rat groups. CONCLUSION: Losartan intervention can markedly reduce pulmonary pressure, inhibit vascular remodeling in volume-overloaded left-to-right shunt rats, and result in down-regulation of HO-1 mRNA expression.

[Protection of HOE642 against cardiomyocyte injury caused by anoxia and reoxygenation].

OBJECTIVE: To investigate the protective effect of calcium antagonists (A/R) injury of cardiomyocytes. METHODS: Primary-cultured cardiomyocytes were divided A/R, A/R+nicardipine(Nic), A/R+HOE642, A/R+H7, A/R+PD98059 and control parameters were measured in all groups, intracellular calcium concentration ([Ca2+]i), content, lactate dehydrogenase (LDH) and creative phosphokinase(CK) activity in the activity. The calpain (u-calpain and m-calpain) protein expression levels were measured In comparison with A/R group, A/R + nicardipine (Nic) and A/R + Nic groups showed [Ca2+]i, m-calpain protein expression, LDH and CK content in the medium, a higher activity of PKC and MAPK (P < 0.01). On the contrary, A/R+H7 and A/R+PD98059 LDH and CK content in the medium, and lower ATP content and cell viability as compared 0. 05). CONCLUSION: The A/R mediated Ca2+ overload resulting from cardiomyocyte injury blocking Ca2+ entry and H+/Na+ exchange, and very likely PKC and MAPK are involved protection against the A/R injury of cardiomyocytes.