Protective role of endogenous hydrogen sulfide in cholecystokinin octapeptid against acute lung injury induced by lipopolysaccharide

AIM: To explore the role of endogenous hydrogen sulfide (H₂S) in the mechanism of cholecystokinin octapeptide (CCK-8) to alleviate acute lung injury (ALI) induced by lipopolysaccharide (LPS). METHODS: Eighty-four Sprague-Dawley rats were randomly divided into seven groups: control, LPS (instilled intratracheally to reproduce the model of ALI), NaHS (H₂S donor) +LPS, propargylglycine ［inhibitor of cysathionine-γ-lyase (CSE), PPG］+LPS, CCK-8+LPS, PPG+CCK-8+LPS and CCK-8 group. Animals were sacrificed at 4 h and 8 h after agent instillation. The wet and dry ratio (W/D) of the lung weight was measured and calculated. Morphological changes of lung tissues were observed. H₂S concentration in plasma, malondialdehyde (MDA) content, myeloperoxidase (MPO) and CSE activities in the lung were determined. Furthermore, the level of P-selectin of lung tissue was measured by radioimmunoassay, the CSE mRNA expression in the lung was detected by RT-PCR, and the protein content in bronchoalveolar lavage fluid (BALF) was detected. RESULTS: Compared with control, severe injury of lung tissues and increase in W/D, protein content in BALF, MDA content, MPO activity and P-selectin level in the lung were observed in rats treated with LPS. LPS also lead to a drop in plasma H₂S concentration, lung CSE activity and CSE mRNA expression. Administration of NaHS before LPS could attenuate the changes induced by LPS, while H₂S concentration, CSE activity and CSE mRNA expression were higher than those in LPS group. However, pre-treatment with PPG exacerbated the lung injury induced by LPS, H₂S concentration, CSE activity and CSE mRNA expression were lower than those in LPS and CCK-8 +LPS group, respectively. CONCLUSION: CCK-8 attenuates LPS-induced acute lung injury by means of anti-oxidation and inhibition of PMN adhesion and aggregation, both of which are mediated by endogenous H₂S.     

Effect of puerarin on monocrotaline-induced pulmonary hypertension and expression of chemokine CX3CL1/fractalkine

AIM: To observe the change of CX₃CL1/fractalkine (FKN) in the rats with monocrotaline-induced pulmonary hypertension, and to study the intervention of puerarin. METHODS: The pulmonary hypertension model was established in vivo by intraperitoneal injection of monocrotaline. Thirty male Sprague-Dawley rats (270-310 g) were randomly divided into 3 groups: control group (C), monocrotaline model group (M)and puerarin treatment group (M+P). The mean pulmonary arterial pressure (mPAP), mean right ventricular pressure (mRVP), mean carotid arterial pressure (mCAP) and the weight ratio of right ventricle (RV) to left ventricle plus septum (LV+S) were also detected. The structural changes of pulmonary arterioles were observed under optical microscope. Remodeling of lung blood vessels was determined by measuring the ratio of vessel wall area to total area (WA/TA) and the medium thickness of pulmonary artery (PAMT). The concentration of soluble fractalkine(sFKN) in plasma was measured by ELISA. The expression of FKN in the pulmonary artery wall was measured by immunohistochemistry. The mRNA level of FKN in the lung tissues was detected by RT-PCR.RESULTS: mPAP, mRVP, RV/(LV+S), WA/TA and PAMT in M group were higher than those in C group (P<0.01). RV/(LV+S), WA/TA and PAMT in M+P group were significantly lower than those in M group (P<0.01). No significant difference of mCAP among the 3 groups was observed. The levels of sFKN, FKN mRNA and FKN protein in M group were higher than those in C group (P<0.01), and the above data in M+P group were lower than those in M group(P<0.05). The serum level of sFKN had a positive correlation with PAMT and RV/(LV+S) (r＝0.719, r=0.685,respectively, P<0.01).CONCLUSION: Puerarin down-regulates the expression of FKN and suppresses the development of pulmonary hypertension and pulmonary vessel remodeling.     

Relationship between thromboxane synthase gene and prostacyclin synthase gene expression and pulmonary hypertension induced by hypoxic hypercapnia

AIM: To study the effect of chronic hypoxic hypercapnia on gene expression of thromboxane synthase and prostacyclin synthase in pulmonary arterioles. METHODS: Sprague-Dawley rats were randomly divided into two groups: control group and hypoxic hypercapnic group. TXS mRNA and PGI₂-SmRNA were observed in pulmonary arterioles by in situ hybridization. RESULTS: mPAP, weight ratio of right ventricle (RV) to left ventricle plus septum(LV+S), contents of TXB₂ and 6-keto-PGF1_α in plasma and lung and TXS mRNAin pulmonary arterioles were much higher in rats of hypoxic hypercapnic group than those of control group. Differences of PGI₂-SmRNA in pulmonary arterioles were not significant in two groups. Light microscopy showed hypertrophy of vessel smooth muscle cells and vessel cavity straitness were found in hypoxic hypercapnic group. CONCLUSION: Changes of gene expressions of thromboxane synthase and prostacyclin synthase and imbalance of TXA₂/PGI₂ may play an important role in hypoxic hypercapnic pulmonary hypertension.     

Effect of L-arginine liposome on L-arginine transport of pulmonary artery in rats chronically exposed to hypoxia-hypercapnia

AIM: To investigate the effect of chronic hypoxia-hypercapnia and L-arginine (L-Arg) liposome on L-Arg transport in rats pulmonary artery. METHODS: Forty Sprague-Dawley rats were randomly divided into four groups, normal control group (NC), chronic hypoxia-hypercapnia group (HH), chronic hypoxia- hypercapnia group+L-Arg (HL) and chronic hypoxia-hypercapnia group+L-Arg liposome (HP). Changes in pulmonary artery L-Arg transport and pulmonary arterial microscopy were observed. RESULTS: (1) The mean pulmonary artery pressure (mPAP) and weight ratio of right ventricle to left ventricle and septum (RV/LV+S) in HH group were higher than those in NC group, and in HP group was lower than that in HH group and HL group, but there was no significant difference between HL group and HH group; (2) At 0.005 mmol/L, 0.01mmol/L, 0.02mmol/L, 0.05 mmol/L, 0.1 mmol/L and 0.2mmol/L concentration of L-Arg, the velocity of L-Arg transport in HH group was lower than that in NC group, and in HL group higher than in HH group, and in HP group was much higher than that in HH group and in HL group. (3) Light microscopy showed that vessel well area/total area (WA/TA) and media thickness of pulmonary arterioles (PAMT) were much higher in rats of HH group than those in NC group, WA/TA and PAMT in HP group were obviously improved. CONCLUSION: The above results indicated that there existed a functional disturbance in L-Arg transport of pulmonary artery in rats chronically exposed to hypoxia-hypercapnia, and it was obviously enhanced when liposome was used as L-Arg carrier. Thus, it appears that liposome-L-Arg may have clinical perspective in the treatment of chronic hypoxic pulmonary hypertension.     

Effect of hypercapnia on lysyl oxidase-dependent collagen cross-linking and hypoxia-induced pulmonary hypertension in rat

AIM: To investigate the effect of hypercapnia on hypoxia-induced pulmonary hypertension and the changes of lysyl oxidase (LOX) and extracellular matrix collagen cross-links in the rat. METHODS: Sprague-Dawley rats were randomly divided into 4 groups:normoxia group, hypoxia group, hypercapnia group and hypoxia+hypercapnia group. LOX activity was detected by fluorescence spectrophotometry. LOX protein expression was detected by immunohistochemistry and Western blot. The mRNA expression of LOX in the pulmonary artery was detected by real-time PCR. RESULTS: The levels of mean pulmonary artery pressure (mPAP), RV/(LV+S) and WA/TA in hypoxia group were significantly higher than those in normoxia group (P<0.01). Moreover, the levels of mPAP and RV/(LV+S) in hypoxia+hypercapnia group were significantly lower than those in hypoxia group (P<0.01). However, no significant difference of mPAP and RV/(LV+S) between hypercapnia group and normoxia group was observed. In hypoxia group, the collagen cross-links in the lung tissue was significantly higher than that in normoxia group and hypercapnia group (P<0.01). Importantly, collagen cross-links in the lung tissue of hypoxia+hypercapnia group was significantly lower than that in hypoxia group (P<0.01). There was no significant difference in collagen cross-links between hypercapnia group and normoxia group. The expression of LOX at mRNA and protein levels and its activity in the pulmonary arteries of hypoxia group were significantly increased as compared with normoxia group (P<0.01). Furthermore, the expression of LOX at mRNA and protein levels and its activity in the pulmonary arteries in hypoxia+hypercapnia group were lower than those in hypoxia group (P<0.01). CONCLUSION: Hypoxia not only up-regulates LOX but also promotes collagen cross-linking in the rat lung, which contributes to the development of pulmonary hypertension. Hypercapnia inhibits hypoxia-induced LOX expression and collagen cross-linking, therefore impairing the progress in hypoxia-induced pulmonary hypertension.     

Effect of ligustrazine on pulmonary arterial pressure and pulmonary arterial wall collagen of chronic hypoxic hypercapnic rats

AIM:To study the effect of ligustrazine on pulmonary hypertensive rats induced by hypoxic hypercapnia. METHODS:Thirty rats were randomly divided into three groups:control group(A),hypoxic hypercapnic group(B), hypoxic hypercapnia+ligustrazine(lig.) group(C). RESULTS: (1) Mean pulmonary arterial pressure(mPAP)of group B was significantly higher than that of group A and mPAP of group C was significantly lower than that of group B(P＜0.01),differences of mean carotid pressure(mCAP) were not significant among three groups (P＞0.05); (2)Electron microscopy and immunohistochemistry showed ligustrazine could inhibit the diposition of collagenous fiber(collagen typeⅠ)in pulmonary arterioles induced by hypoxic hypercapnia; (3) Plasma endothelin level of group C was significantly lower than that of group B (P＜0.01), serum (NO ₂^-/NO₃^-) of group C was significantly higher than that of group B (P＜0.01). CONCLUSION:Ligustrazine can inhibit pulmonary hypertension and the diposition of collagen type Ⅰ in pulmonary arterial wall induced by hypoxic hypercapnia.     

Relationship between expression of heme oxygenase-1 mRNA and pulmonary hypertention induced by hypoxic hypercapnia

AIM: To study the effect of chronic hypoxic hypercapnia on expression of heme oxygenase-1 (HO-1). METHODS: Sprague-Dawley rats were randomly divided into three groups: control group(A),hypoxic hypercapnic group(B), hypoxic hypercapnia+hemin group(C). HO-1 and HO-1 mRNA were observed in pulmonary arterioles by the technique of immunohistochemistry and in situ hybridization. RESULTS: ① mPAP and weight ratio of right ventricle (RV) to left ventricle plus septum (LV+S) were significantly higher in rats of B group than those of A and C group (P<0.01). Differences of mCAP were not significant in three groups(P>0.05). ② Blood CO concentration was significantly higher in rats of B group than that of A group (P<0.01), it was much higher in C group than that of B group(P<0.01). ③ Light microscopy showed that vessel well area/total area (WA/TA), density of medial smooth muscle cell (SMC) and media thickness of pulmonary arterioles were much higher in rats of B group than those of A and C group (P<0.01). ④ The observation by electron microscopy showed proliferation of medial smooth muscle cells and collageous fibers of pulmonary arterioles in rats of B group, hemin could reverse the changes mentioned above. ⑤ HO-1 and HO-1 mRNA in pulmonary arterioles was significantly higher in rats of B group than those of A group(P<0.01), and they were significantly higher in rats of C group than those of B group (P<0.01). CONCLUSION: Expression of HO-1 mRNA and HO-1 in pulmonary arterioles was enhanced by hypoxic hypercapnia. Hemin partly inhibited pulmonary hypertension and pulmonary vessel remodeling by enhancing the expression of HO-1 mRNA and HO-1.     

The regulation of nitric-oxide synthase/nitric-oxide system by endogenous carbon monoxide in rats with pulmonary hypertension

AIM:To study the role and the mechanism of heme oxygenas/endogenous carbon monoxide on nitric oxide synthase/nitric oxide system in rats with pulmonary hypertension induced by hypoxic hypercapnia.METHODS:Sprague-Dawley rats were randomly divided into three groups: control group (A group), hypoxic hypercapnic group (B group), hypoxic hypercapnia+hemin group (C group). Blood CO concentration (COHb%), NO concentration, HO-1 activity, iNOS, cNOS in blood serum and lung homogenate were measured, respectively. RESULTS:① mPAP and RV/(LV+S) of B group were significantly higher than those of A and C group(P＜0.01).② Blood CO concentration, activity of HO-1in blood serum and lung homogenate in rats of B group were significantly higher than those of A group, but were significantly lower than those of C group (P＜0.01). ③ NO concentration in blood serum and lung homogenate in rats of B group were significantly lower than those of A group, those of C group were significantly higher than those of B group (P＜0.01).④The activity of iNOS in blood serum and lung homogenate in rats of B group were significantly higher than those of A group, but were significantly lower than those of C group (P＜0.01). Activity of cNOS in blood serum and lung homogenate of B group were significantly lower than those of A group (P＜0.01), and there was no significant difference between cNOS in B and C group.CONCLUSION:Endogenous carbon monoxide upregulated iNOS/NO system in rats with chronic pulmonary hypertension induced by hypoxic hypercapnia.     

Effect of Panax notoginoside on pulmonary arterial pressure and expression of p38 MAPK in lung tissues of hypoxic rats

AIM: To observe the effect of Panax notoginoside (PNS) on the pulmonary artery pressure and the p38 mitogen-activated protein kinase(p38 MAPK) in lung tissues of rats treated with hypoxia. METHODS: Thirty adult male SD rats were randomly divided into 3 groups. The rats in normal control group were exposed to normal conditions, the rats in hypoxia group were exposed to isobaric hypoxia, and the rats in hypoxia+PNS group were treated with PNS under the condition of hypoxia. After 4 weeks of treatment, the mean pulmonary arterial pressure (mPAP) and the mean carotid arterial pressure (mCAP) were measured by cardiac catheterization. The heart was isolated, and the right ventricle (RV), left ventricle plus ventricular septum (LV+S) were weighed to calculate the ratio of RV/(LV+S).The quantity of phospho-p38 MAPK(p-p38 MAPK) in rat pulmonary arterioles was determined by the method of immunohistochemistry and the mRNA content of p38 MAPK was tested by RT-PCR. RESULTS: The mPAP and RV/(LV+S) in hypoxia group were higher than those in normal control group. The expression of p-p38 MAPK in rat pulmonary arterioles and p38 MAPK mRNA in the lung tissues were higher than those in normal control group (P<0.05). The mPAP, RV/(LV+S), the expression of p-p38 MAPK in rat pulmonary arterioles and p38 MAPK mRNA in the lung tissues in hypoxia+PNS group were significantly lower than those in hypoxia group (P<0.05).CONCLUSION: PNS possesses the preventive and therapeutic effect on hypoxic pulmonary hypertension by decreasing p-p38 MAPK and down-regulation of p38 MAPK mRNA in the lungs.     

Changes of interleukin-6 in pulmonary hypertension mice induced by chronic hypoxic-hypercapnia

AIM: To investigated the changes of interleukin-6 (IL-6) in the pulmonary hypertension mice induced by chronic hypoxic hypercapnia. METHODS: Sixteen male C57BL/6 mice were randomly divided into 2 groups (8 mice in each group): normal control group and chronic hypoxic hypercapnia group. The mice in chronic hypoxic hypercapnia group were placed in a sealed chamber where O₂ concentration was kept at 9%~11%, and the CO₂ concentration at 5% ~6%, 8 h a day, 6 days a week for 4 weeks. The right ventricular (RV) weight, the weight of left ventricle plus ventricular septum (LV+S) were measured and right ventricular hypertrophy index was calculated. The structural changes of the pulmonary arteries were assessed by the method of histology with HE staining. The vessel wall diameter/total diameter (WT%) and the vessel wall area/total area (WA%) were analyzed by Image-Pro Plus 6.0 software. The protein expression of IL-6 in the lungs of the mice was determined by immunohistochemistry and ELISA, and the mRNA expression of IL-6 in the lungs was determined by RT-PCR. RESULTS: Compared with control group, RV/(LV+S), MT%, MA% and the expression of IL-6 at mRNA and protein levels were significantly increased in chronic hypoxic hypercapnia group. CONCLUSION: In the environment of chronic hypoxia and hypercapnia, the expression of interleukin-6 was elevated in mouse lungs, which may closely related to the development of pulmonary hypertension.     

Effect of safflower injection on expression of COX-2 mRNA and protein in chronic hypoxic hypercapnic rat pulmonary arterioles

AIM:To study the effect of safflower injection on expression of COX-2 mRNA in chronic hypoxic hypercapnic rat pulmonary arterioles.METHODS: Sprague-Dawley rats were randomly divided into normal control group, hypoxic hypercapnic group (B), hypoxic hypercapnia+ safflower injection group (C). The concentration of TXB2 and 6-Keto-PGF1α in plasma and in lung were detected by the technique of radioimmunoassay. COX-2 mRNA was observed in arterioles from rats by the technique of in situ hybridization. RESULTS: ① Mean pulmonary arterial pressure(mPAP), weight ratio of right ventricle (RV) to left ventricle plus septum (LV+S) were much higher in B group than those in control group. No significant difference of mean carotid arterial pressure(mCAP) was observed in three groups. ② The concentration of TXB2 and the ratio of TXB2/6-keto-PGF1α were significantly higher in B group than those in control group. ③ Light microscopy showed that vessel wall area/total area, the density of medial smooth muscle cells and the thickness of medial smooth cell layer were significantly higher in B group than those in control group. Electron microscopy showed proliferation of medial smooth muscle cells and collagenous fibers in pulmonary arterioles in B group. Safflower injection reversed the changes mentioned above. ④ Expression of COX-2 mRNA in pulmonary arterioles was much higher in C group than those in B group. Differences of COX-1 mRNA in pulmonary arterioles were not significant between these two groups.CONCLUSION:Safflower injection increases the expression of COX-2 mRNA in chronic hypoxic hypercapnic rat pulmonary arterioles, indicating an important mechanism that safflower injection inhibits the formation of hypoxic hypercapnia pulmonary hypertension and pulmonary vessel remodeling.     

The effect of L-arginine on protein kinase C of isolated pulmonary arterial rings from rats with hypoxia-induced pulmonary hypertension

AIM: To elucidate whether the mechanism that L-arginine can relieve hypoxia pulmonary hypertension involves inhibition of the activity of protein kinase C(PKC).METHODS: Twenty-one male Wistar rats were randomly divided into NS control, hypoxia and L-arginine(500 mg·kg^-1·d^-1, ip) treatment groups. After two-weeks treatment, mean pulmonary artery pressure (mPAP), mean systematic artery pressure (mSAP) and the ratio of the weight of right ventricle to that of left ventricle plus septum were measured, then two pulmonary arterial rings were isolated to be exposed to PDBu(a specific activator of PKC ) and observed: (1) The maximal response (P₁) to 500 nmol/L PDBu, the time required to achieve a half-maximal response to 500 nmol/L PDBu (t_1/2), the time during which the maximal response to 500 nmol/L PDBu maintained (T) and the isometric responses at different times (2, 4, 8, 12, 20, 40, 60, 80 min). The isometric response was represented as the percentage of the maximal response (P₀) of the same arterial ring to 5μmol/L phenylephrine hydrochloride (P₀%). (2) Dose-response curve in response to PDBu (10-11 000 nmol/L) and the dose producing a half-maximal response in the curve (EC₅₀). RESULTS: mPAP, RV/(LV+S), P₁, T and the isometric responses at 2, 4, 8, 20 min of NS control and L-arginine treatment groups were lower than those of hypoxic group respectively (P＜0.05), while t_1/2 and EC₅₀ were all greater than those of hypoxic group respectively (P＜0.05).CONCLUSION: The activity of PKC was augmented when rats were exposed to two-weeks normobaric hypoxia, which resulted in the increased reactivity of the isolated pulmonary arterial rings. L-arginine can inhibit the activation of PKC, which is likely part of the mechanism by which L-arginine can reduce mPAP and relieve the hypertrophy of right ventricle.     

Protective effect of salidroside on rats with hypoxic pulmonary hypertension by suppressing oxidative stress

AIM: To study whether salidroside plays a protective role in hypoxia-induced pulmonary hypertension by suppressing oxidative stress. METHODS: Sprague-Dawley rats were randomly divided into 4 groups:normoxia (N) group, hypoxia for 4 weeks (H₄) group, low-dose salidroside (hypoxia for 4 weeks and treatment with salidroside at 16 mg/kg, H₄S16) group and high-dose salidroside (hypoxia for 4 weeks and treatment with salidroside at 32 mg/kg, H₄S32) group. The mean pulmonary arterial pressure (mPAP), the weight ratio of right ventricle/(left ventricle+septum)[RV/(LV+S)] and vessel wall area/vessel total area (WA/TA) were evaluated. The levels of malondialdehyde (MDA) in the serum and lung tissues were detected by colorimetric method. The levels of 8-iso-prostaglandin F_2α (8-iso-PGF_2α) in the serum and lung tissues were measured by ELISA. The activity of superoxide dismutase (SOD) in the serum was analyzed by hydroxylamine method. The expression of NAPDH oxidase 4 (NOX4) and SOD1 in the lung tissues was determined by Western blot. RESULTS: Compared with N group, the levels of mPAP, RV/(LV+S) and WA/TA in H₄ group were significantly increased, which were apparently attenuated by salidroside injection in a dose-dependent manner. Meanwhile, salidroside administration apparently decreased the levels of MDA and 8-iso-PGF_2α in the serum and lung tissues, as well as the expression of NOX4 in the lung tissues. Besides, compared with N group, the activity of SOD in the serum and the expression of SOD1 in the lung tissues in H₄ group were significantly decreased, while administration of salidroside increased the activity of SOD in the serum and the expression of SOD1 in the lung tissues in a dose-dependent manner. CONCLUSION: Salidroside protects the pulmonary vessels from remodeling and attenuates hypoxia-induced pulmonary hypertension by inhibiting oxidative stress.     

Effects of A2a adenosine receptor on hypoxic pulmonary hypertension in rats treated with salidroside

AIM: To study the protective effect of A_2a adenosine receptor (A_2aAR) on hypoxic pulmonary hypertension in the rats treated with salidroside. METHODS: Sprague-Dawley rats were randomly divided into 6 groups: normal control group, hypoxia group, hypoxia+salidroside (low dose) group, hypoxia+salidroside (median dose) group, hypoxia+salidroside (high dose) group, and hypoxia+CGS-21680 (a selective agonist of A_2aAR) group. Pulmonary hypertension in the rats was produced for 4 weeks. Mean pulmonary artery pressure (mPAP), mean carotid arterial pressure (mCAP) and the weight ratio of right ventricle/(left ventricle+septum)［RV/(LV+S)］ were measured. The expression of A_2aAR in the pulmonary arterioles was determined by immunohistochemistry and in situ hybridization. The mRNA expression of A2aAR in the lung tissues was detected by real-time RT-PCR. The protein level of A_2aAR in the lung tissues was analyzed by Western blotting. RESULTS: The mPAP in hypoxia group was significantly higher than that in normal control group. The mPAP in hypoxia+salidroside (high dose) group and CGS-21680 group was significantly lower than that in hypoxia group. RV/(LV+S) in hypoxia group were significantly higher than that in normal control group. RV/(LV+S) in hypoxia+salidroside (median dose) group, hypoxia+salidroside (high dose) group and CGS-21680 group were lower than that in hypoxia group. The ratio of vessel wall area/vessel total area (WA/TA) in hypoxia group was significantly higher than that in normal control group. WA/TA in hypoxia+salidroside (low dose) group, hypoxia+salidroside (median dose) group, hypoxia+salidroside (high dose) group and CGS21680 group were obviously lower than that in hypoxia group. The expression of A_2aAR was significantly higher in hypoxia group than that in normal control group. The expression of A_2aAR in hypoxia+salidroside (high dose) group and CGS-21680 group was obviously higher than that in hypoxia group. CONCLUSION: The A_2aAR attenuates pulmonary vessel remodeling and pulmonary hypertension induced by hypoxia. Salidroside protects the pulmonary vessel from remodeling and inhibits the development of hypoxia-induced pulmonary hypertension by up-regulation of A_2aAR expression.     

Expression and distribution of 5-HT1B receptors in lung tissue in rats with hypoxic pulmonary hypertension

AIM: To investigate the changes of 5-hydroxytryptamine(5-HT)levels and to observe the expression and distribution of 5-HT_1B receptors in the lung tissues of hypoxic pulmonary hypertension(HPH) rats for exploring the mechanisms of hypoxic pulmonary hypertension.METHODS: Forty male Sprague-Dawley rats were randomly divided into 4 groups: normoxia control(control group), 3 weeks hypoxia group, 4 weeks hypoxia group and 5 weeks hypoxia group. The rats in normoxia control group stayed in normal environment. The rats in 3 weeks hypoxia group, 4 weeks hypoxia group and 5 weeks hypoxia group were kept respectively in hypoxia chamber for 3 weeks, 4 weeks and 5 weeks respectively to establish the HPH animal model. After HPH was established, the mean pulmonary pressure(mPAP) and the right ventricular systolic pressure(RVSP) were recorded by a micro-catheter. RV/(LV+S) ratio was calculated to assess the right ventricular hypertrophy. 5-HT levels in plasma and lung tissues of HPH rats were measured by ELISA. The expression and distribution of 5-HT_1B receptors in the lung tissues were measured by the methods of immunohistochemistry and Western blotting. RESULTS: Compared to the normoxia controls, mPAP, RVSP and RV/(LV+S)% in 3 weeks hypoxic rats increased significantly(P<0.05), and continued to increase following prolonged hypoxia. The results of ELISA showed that 5-HT levels in plasma and lung tissues of HPH rats continued to increase following prolonged hypoxic exposure(P<0.05). The 5-HT_1B receptors were localized mainly in the intima of the pulmonary arteries in normal rats. Exposed to hypoxia, the immuno-reactivity for 5-HT_1B receptors increased in the media of pulmonary arteries in 3 weeks hypoxic rats, particularly those bordering the adventitia. The increase in the expression of 5-HT_1B receptor was observed following prolonged hypoxic exposure. The results of Western blotting showed the same changes of 5-HT_1B receptor expression in the lung tissues as that of 5-HT_1B immuno-reactivity in pulmonary arteries.CONCLUSION: Hypoxia induces the high 5-HT levels and the over-expression of 5-HT_1B receptors in the pulmonary arteries of HPH rats, indicating the underlying mechanism of 5-HT in the development of HPH.     

“中国园艺学会第七届青年学术讨论会”

中国园艺学会第九届第8次常务理事扩大会决定，“中国园艺学会第七届青年学术讨论会”由山东农业大学园艺科学与工程学院和山东省园艺学会承办，将于2006年7月或8月在山东泰安举行。     

Expression and distribution of osteopontin in the development of pulmonary hypertension induced by hypoxia-hypercapnia

AIM: To study the expression and distribution of osteopontin (OPN) in lungs and pulmonary arteries in pulmonary hypertensive rats induced by hypoxia-hypercapnia, and to explore the role of OPN in pathogenesis of pulmonary hypertension. METHODS: Forty-eight male Sprague-Dawley rats (Weight 180 g-220 g) were randomly divided into four groups: normal control group (NC), hypoxic hypercapnia 1-week，2-week and 4-week group (1HH, 2HH and 4HH). The expressions of OPN mRNA and protein in lungs and pulmonary arteries were detected by RT-PCR and immunohistochemistry. ELISA was used to detect the concentration of OPN in lung homogenates. The content of OPN in pulmonary arteries was detected by Western blotting. RESULTS: ① The mean pulmonary artery pressure (mPAP) and weight ratio of right ventricle to left ventricle and septum ［RV/(LV+S)］ in all hypoxic hypercapniac groups were higher than those in normal control group (P<0.01), respectively. Differences of mean carotid artery pressure (mCAP) among these four groups were not significant (P>0.05). ② The expression of OPN mRNA was significantly increased in pulmonary arteries and lung tissues in hypoxic hypercapnic groups compared with normal control group (P<0.01). ③ The result of immunohistochemistry showed that OPN was only detected in bronchus and alveolar epithelium, but not detected in pulmonary arterioles of normal control group. In contrast，OPN expression was evident in pulmonary arterioles of 1HH rats，especially in media. Moreover, the expression of OPN was markedly increased in group 2HH and 4HH. ④ OPN levels in lung homogenates in 1HH, 2HH and 4HH were increased by 69%, 128% and 187% (P<0.01), respectively, compared with control rats. ⑤ Western blotting analysis showed that the contents of OPN were significantly higher in all hypoxic hypercapnic groups than those in NC group (P<0.01).CONCLUSION: The expressions of OPN in pulmonary arteioles and lung are increased in rats with pulmonary hypertension. OPN might play an important role in the pathogenesis of pulmonary hypertension induced by chronic hypoxia and hypercapnia.     

Effect of ligustrazine on hydrogen sulfide system in lung tissue of rats with pulmonary hypertension induced by hypoxic hypercapnia

AIM: To investigate the effect of ligustrazine on hydrogen sulfide (H2S) system in pulmonary hypertension induced by hypoxic hypercapnia in rats. METHODS: Thirty Sprague-Dawley rats were randomly divided into 3 groups: control group (C), hypoxic hypercapnia group (HH), and hypoxic hypercapnia+ligustrazine group (HH+L). The change of hemodynamics was measured. The ratio of vessel wall area and total area of arteriae pulmonalis were observed under light microscope. The apoptosis of arteriae pulmonalis was tested with TdT-mediated dUTP nick end labeling (TUNEL), and the apoptosis index was calculated. Plasma level of hydrogen sulfide and activity of hydrogen sulfide generating enzymes in homogenates of rat lung tissue were evaluated by sensitive modified sulfide electrode method. Cystathionine-γ-lyase (CSE) mRNA in lung tissues was determined by RT-PCR. RESULTS: The level of mean pulmonary arterial pressure, the ratio of vessel wall area/total area and the right ventricle/left ventricle+septum were significantly higher in HH group than those in C group, and the value was obviously lower in HH+LTZ group than that in HH group (all P<0.01). The mean carotid arterial pressure of 3 groups had no significant difference (P>0.05). The apoptotic index of arteriae pulmonalis in HH group and HH+LTZ group was significantly lower than that in C group, and that in HH+LTZ group was significantly higher than that in HH group (P<0.05 or P<0.01). Plasma level of H2S, the activity of H2S generating enzymes in homogenates of rat lung tissue, cystathionine-γ-lyase (CSE) mRNA in lung tissues in HH group were significantly lower than those in C group (all P<0.01), and those in HH+LTZ group were significantly lower than those in HH group (all P<0.01). CONCLUSION: Ligustrazine up-regulates the expression of cystanthionine-γ-splitting enzyme (CSE), enhances the activity of CSE and increases the level of H2S to prevent pulmonary hypertension induced by hypoxic hypercapnia.