Changes of apoE protein expression in lung of mice with hypoxic pulmonary arterial hypertension / 中国应用生理学杂志

OBJECTIVE@#To observe the changes of apolipoprotein E (apoE) protein expression of pulmonary tissue in mice with pulmonary hypertension induced by hypoxia.@*METHODS@#The animal model of hypoxic pulmonary hypertension was established by exposing the mice to isobaric hypoxic chamber for 3 weeks (23 h/d, regular chow feed).Twenty male wild type (WT) C57BL/6 mice and twenty apoE gene knockout (apoE-KO) mice were randomly divided into normoxia group and hypoxia group. The plasma concentrations of low density lipoprotein (LDL), high density lipoprotein (HDL) and total cholesterol were detected by ELISA method. The protein expression of apoE in lung and liver, and peroxisome proliferators-activated receptor gamma (PPARγ) in lung were measured by Western blot.@*RESULTS@#①In WT mice, the right ventricular systolic pressure (RVSP) and the weight ratio of right ventricle (RV) to left ventricle plus septum (LV+S) of hypoxia group were significantly higher than those of normoxia group by 68% and 59% (<0.05), respectively. The plasma concentration of HDL and HDL/LDL of hypoxia group were significantly lower than those of normoxia group by 17% and 40% (<0.05), respectively.The protein expression of apoE in lung and in liver of hypoxia group were significantly down-regulated than those of normoxia group by 48% and 52% (<0.05), respectively.The protein expression of PPARγ in lung was significantly down-regulated than that of normoxia group by 37%(<0.05).RVSP were significantly negative correlated with the protein levels of apoE and PPARγ in lung (<0.01).② In apoE-KO mice, RVSP and the weight ratio of RV to LV+S of hypoxia group were significantly higher than those of normoxia group by 96% and 86% (<0.05), respectively.RVSP and RV to (LV+S) of hypoxia group in apoE-KO mice were significantly higher than those of hypoxia group in WT mice by 29% and 24% (<0.05), respectively.@*CONCLUSIONS@#Down-regulated expression of apoE in lung tissue participates in the pathological proceeding of pulmonary hypertension induced by hypoxia.

Effect of apelin on vasodilatation of isolated pulmonary arteries in rats is concerned with the nitric oxide pathway / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To investigate the effect of apelin on vasodilatation of isolated pulmonary arterial rings in rats and its relationship to the nitric oxide (NO) pathway, and to observe the difference of vasodilatation between hypoxic rats and normoxic rats.</p><p><b>METHODS</b>Thirty-six male Sprague-Dawley (SD) rats were randomly divided into hypoxic group and normoxic group. The effects of accumulated apelin on pulmonary arterial rings preconstricted with norepinephrine (NE) were observed by using tissue organ bath system. After pulmonary arterial rings were pretreated with three methods: removing the endothelium, pretreating with nitric oxide synthase inhibitor L-NAME or soluble guanylatecyclase inhibitor ODQ, the different effect of apelin was observed. In addition, the difference of vasodilatation between hypoxic rats and normal rats were observed.</p><p><b>RESULTS</b>(1) Exposure of intact endothelium pulmonary arterial rings preconstricted by NE to apelin at concentration (0.01 - 100 nmol/L) induced a significant concentration dependent relaxation. The maximal vasorelaxant effect of apelin was 10.62% +/- 2.60%, which was inhibited by removal of the endothelium (P < 0.01), pretreatment with L-NAME (P < 0.01) or ODQ (P < 0.01). (2) Response of pulmonary arterial rings from hypoxic pulmonary hypertension rats was decreased (P < 0.05). Compared to normal rats, at a concentration of 100 nmol/L, the response to apelin on arteries from hypoxic rats decreased 60.45% (P < 0.01). But the values of EC50 were not significantly different (P > 0.05).</p><p><b>CONCLUSION</b>These results indicate that apelin relaxes the pulmonary arterial rings of rats in an endothelium dependent manner, which may have a relationship to NO signaling pathway. The response of vasodilatation is decreased in the pulmonary arterial rings from the hypoxic rats.</p>

Changes of endoplasmic reticulum stress-induced apoptosis in pulmonary tissue of rats with hypoxic pulmonary hypertension / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To investigate the changes of endoplasmic reticulum stress-induced apoptosis in pulmonary tissue of rats with hypoxic pulmonary hypertension.</p><p><b>METHODS</b>Twenty two male SD rats were randomly divided into control group and 4-week hypoxia-hypercapnia group (n=11). The mean pulmonary arterial pressure (mPAP) and the mean carotid arterial pressure (mCAP) were monitored, and the weight ratio of right ventricle (RV) to left ventricle plus septum (LV + S) were measured. The rattish pathological model were assessed by mPAP, mCAP, RV/(LV+ S), vessel wall area/total area (WA/TA), vessel cavity area/total area (CA/TA) and media thickness of pulmonary arteriole (PAMT). The pulmonary apoptotic cells were detected by Hoechst staining. RT-PCR was used to study the genetic expression of caspasel2, glucose regulated protein 78 (GRP78) and GRP94 in pulmonary tissue. The expression of GRP94 and GRP78 proteins in pulmonary tissue were determined by using immunohistochemistry.</p><p><b>RESULTS</b>(1) (The mPAP, RV/(LV + S), WA/TA and PAMT were respectively higher by 50.5%, 37.3%, 72.5% and 137% in hypoxic group than those in control group, while CA/TA was lower by 41.9% (all P < 0.01). There was not significant difference of mCAP between the two groups. (2) Hoechst staining showed that the pulmonary apoptotic cells in hypoxic group outnumbered markedly than those in control group, and the apoptotic cells were mainly in pulmonary tissue, while they were rare in pulmonary vascular smooth muscle cell. (3) Compared with control group, the expression of pulmonary caspasel2, GRP78 and GRP94 mRNA in hypoxic group were higher by 144%, 137% and 80.7% (all P < 0.05), respectively. (4) The expression of pulmonary GRP78 and GRP94 proteins were up-regulated in hypoxic group, and these proteins mainly localized in pulmonary vascular endothelial cell.</p><p><b>CONCLUSION</b>The endoplasmic reticulum stress-induced apoptosis may be one of the mechanism of hypoxic pulmonary hypertension and pulmonary vascular wall remodeling.</p>

Protective and therapeutic effect of apelin on chronic hypoxic pulmonary hypertension in rats / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To study the role of apelin in the prevention of pulmonary hypertension induced by hypoxia in rats.</p><p><b>METHODS</b>The animal model of hypoxic pulmonary hypertension was established by exposing the rats to isobaric hypoxic chamber for 4 weeks (8 h/d, 6 d/ w). Forty male Sprague-Dawley rats were randomly divided into control group (NC), hypoxic group(HH), hypoxic with low-dose apelin (5 nmol/(kg x d) group(LA) and high-dose apelin (10 nmol/(kg x d) (HA). [pGlu]apelin-13 was administered into the rats of apelin groups by mini-osmotic pump subcutaneously. The mean pulmonary arterial pressure(mPAP) and the mean carotid arterial pressure (mCAP) were measured by either right or left cardiac catheterization, and the weight ratio of right ventricule/left ventricule plus septum (RV/(LV + S)) were calculated. The Masson's trichrome stained lung specimens were examined by light microscope to examine the vessel wall area/total area (WA/TA), vessel cavity area/total area (CA/TA) and media thickness of pulmonary arterioles (PAMT). Meanwhile, the lung homogenates were assayed for the activity of supeeroxide dismutase (SOD) and the content of malondialdehyde (MDA).</p><p><b>RESULTS</b>(1) mPAP and RV/(LV + S) of HH group were significantly higher than those of NC group. mPAP of LA and HA groups were lower than those of HH group. The RV/(LV + S) of HA group was significantly lower than that of HH group, but there was no significant difference between HH group and LA group. (2) Masson's trichrome staining revealed that WA/TA and PAMT of HH group were higher than those of NC group. Administration of apelin significantly eliminated WA/TA and PAMT in LA and HA groups. (3) CA/TA of HH group was lower than that of NC group. Administration of apelin significantly elevated CA/TA in LA and HA groups. (4) The activity of SOD and content of MDA in HH group was, respectively, lower and higher than those in NC group. Apelin treatment increased the activity of SOD in LA and HA groups while decreased the content of MDA.</p><p><b>CONCLUSIONS</b>Apelin could play an important role in treatment of hypoxic pulmonary hypertension of rats and the mechanisms of protection were associated with vasodilation of pulmonary artery and inhibition of oxidative stress.</p>

Effect of hypoxia on the expressions of intermedin/ adrenomedullin2 in plasma and the tissues of heart and lung in rats / 中国应用生理学杂志

<p><b>AIM</b>To study the effect and significances of two-week hypoxia on the expression of intermedin/adrenomedullin2 (IMD/ADM2) in plasma and the tissues of heart and lung in rats.</p><p><b>METHODS</b>Twenty male SD rats were randomly divided into normal control group and hypoxia group. The concentrations of IMD/ADM2 and adrenomedullin (ADM) in plasma, right ventricle and lung tissue were measured by radioimmunoassay. RT-PCR was used to detect the mRNA levels of IMD/ADM2 and ADM in right ventricle and lung tissue.</p><p><b>RESULTS</b>(1) The mean pulmonary arterial pressure (mPAP) and the weight ratio of right ventricle (RV) to left ventricle plus septum (LV + S) of hypoxia group were significantly higher than those of normal control group (P < 0.01). (2) The concentrations of IMD/ADM2 and ADM in plasma were significantly higher in hypoxia group, compared with normal control group (P < 0.01). (3) The concentration of ADM in right ventricle and lung tissue in hypoxia group was significantly higher than that in normal control group (P < 0.01), while there was no significant difference in IMD/ADM2 between the two groups. (4) The mRNA levels of IMD/ADM2 and ADM in right ventricle and lung tissues were significantly up-regulated in hypoxia group (P < 0.05).</p><p><b>CONCLUSION</b>The expressions of IMD/ADM2 peptides and gene in plasma, right ventricular and pulmonary tissues are different in the early-middle pathological proceeding of pulmonary hypertension induced by two-week hypoxia in rats.</p>

Effect of apelin on hypoxic pulmonary hypertension in rats: role of the NO pathway / 生理学报

To investigate the effectiveness and mechanism of apelin against pulmonary hypertension and pulmonary vascular remodeling induced by hypoxia in rats, 24 male Sprague-Dawley rats were randomly divided into normal control (NC) group, 4-week hypoxia (HH) group and 4-week hypoxia with apelin (HA) group (each n=8). The rats of hypoxic group were placed in an isobaric hypoxic chamber, in which O₂ and CO₂ content was maintained at 9%-11% and <3%, respectively, for 4 weeks (8 h/d, 6 d/week). [pGlu]apelin-13 (10 nmol/kg per day, 28 d) was administered subcutaneously by osmotic mini-pump before hypoxia treatment in HA group. L-arginine (L-Arg) uptake of pulmonary artery was assay by [³H]-L-Arg, while nitric oxide synthase (NOS) activity of pulmonary tissue, and nitrate/nitrite (NO₂(-)/NO₃(-)) concentrations in pulmonary tissue and plasma were detected by colorimetric technique and nitrate reductase method, respectively. The results showed that mean pulmonary arterial pressure, the ratio value of right ventricle weight to left ventricle plus septum weight, the relative medial thickness, and the relative medial area of pulmonary arterioles were higher in HH group than those in NC group (all P<0.01), while these indices were lower in HA group than those in HH group (P<0.05 or P<0.01). Compared with those in HH group, the uptake of 0.5, 5 and 10 nmol/L [³H]-L-Arg in pulmonary artery in HA group increased by 121.4% (P<0.01), 85.0% (P<0.05) and 61.5% (P<0.05), respectively; cNOS activity of pulmonary tissue increased by 74.3%, while iNOS activity decreased by 25.0% (all P<0.01); and NO₂(-)/NO₃(-) concentrations in pulmonary tissue and plasma increased by 97.6% and 48.0% (all P<0.05), respectively. Taken together, our results suggest that apelin has a prophylactic effect against hypoxic pulmonary hypertension in rats, and that the mechanism of this effect is possibly associated with activation of the L-Arg/NOS /NO pathway.

Effects and relationship between NO and HIF-1alpha in rats with pulmonary hypertension induced by hypoxia / 中国应用生理学杂志

<p><b>AIM</b>To investigate the expression of hypoxia-inducible factor-1 alpha (HIF-1alpha) in rats with chronic pulmonary hypertension induced by hypoxia and hypercapnia and its relationship with nitric oxide(NO).</p><p><b>METHODS</b>Fourty male Sprague-Dawley rats were randomly divided into four groups, normal control group (NC), hypoxia-hypercapnia group (HH), hypoxia - hypercapnia + L-arginine liposome group(HP) and hypoxia-hypercapnia+ N-nitro-L-arginine methylester group (HM). Colorimetric analysis, immunohistochemistry and in situ hybridization were used for detection of NO, HIF-1alpha and constitutive nitric oxide synthase (ecNOS).</p><p><b>RESULTS</b>(1) The mean pulmonary arterial pressure (mPAP) and the weight ratio of right ventricular to left ventricle plus septum (RV/(LV + S)) of HH group were higher than those of NC group (P < 0.05), HP group much lower than HH group (P < 0.01), mPAP of HM higher than HH group ( P < 0.05). 2)0 Contents of NO in plasma and pulmonary tissue homogenates of HH group were much lower than those of NC group (P < 0.01), HP group higher than HH group (P < 0.01). There were no difference between HM group and HH group. (Expression of HIF-1alpha and HIF-1alpha mRNA in pulmonary arterioles of HH group were significantly higher than those of NC group( P < 0.01), HP group lower than HH group (P < 0.01) ,HM group higher than HH group (P < 0.01); Whereas expression of ecNOS and ecNOS mRNA in pulmonary arterioles of HH were lower than those of NC group( P < 0.05, IP group higher than HH group (P < 0.01), HM group lower than HH group (P < 0.05).</p><p><b>CONCLUSION</b>HIF-1alpha is involved in the pathogenesis of chronic pulmonary hypertension induced by hypoxia and hypercapnia. The protective function of NO in the pathogenesis might be partly depended on its effects on the expression/activity of HIF-1alpha in lung.</p>

Effect of L-arginine liposome on nitric oxide content and nitric oxide synthase gene expression in rats chronically exposed to hypoxia and hypercapnia / 中国应用生理学杂志

<p><b>AIM</b>To investigate the effects of L-arginine liposome on nitric oxide(NO) and nitric oxide synthase gene (NOS mRNA) in rats chronically exposed to hypoxia-hypercapnia.</p><p><b>METHODS</b>Fourty male SD rats were randomly divided into four groups (n=10): normal control group(NC), hypoxia-hypercapnia group (HH), hypoxia-hypercapnia + L-arginine group(HL) and hypoxia-hypercapnia + L-arginine liposome group (HP). Contents of NO in plasma were measured using colorimetric analysis. Expression of nitric oxide synthase gene were measured with situ hybridization.</p><p><b>RESULTS</b>(1) The mean pulmonary artery pressure(mPAP) and weight ratio of right ventricle to left ventricle and septum(RV/LV + S) of HP group were obviously lower than those of HH group and HL group. (2) The NO contents in plasma of HP group were obviously higher than those of HH group and HL group (P < 0.01). (3) Situ hybridization showed the average value of integral light density(LD) of ecNOS mRNA in pulmonary arterioles was significantly higher in rats of HP group than that of HH group and HL group (P < 0.01). (4) Light microscopy showed WA/TA (vessel wall area/total area) and PAMT (media thickness ratio of pulmonary arterioles) were significantly lower in rats of HP group than those of HH group (P < 0.01).</p><p><b>CONCLUSION</b>L-arginine liposome could lower the mPAP and lighten the remodeling of pulmonary arterioles of the rats chronically exposed to hypoxia-hypercapnia than L-arginine does. It suggests that L-arginine liposome significantly promotes the membrane transportin of L-arginine.</p>

Effect of puerain on Apelin/APJ system in right ventricle of pulmonary hypertensive rats induced by hypoxia-hypercapnia / 中草药

Objective To investigate whether the effect of puerarin on right ventricle hypertrophy of pulmonary hypertensive rats induced by chronic hypoxia-hypercapnia was related to new peptide Apelin or its receptor(APJ).Methods Thirty male Sprague-Dawley rats were randomly divided into three groups, they are control group,hypoxia-hypercapnia 4-week model group,and hypoxia-hypercapnia 4-week plus puerarin group.The concentrations of Apelin-36 protein in plasma and homogenate of right ventricular muscle were detected by radioimmunoassay.The mRNA expressions of Apelin and APJ in right ventricu- lar muscle were measured by semi-quantitive reverse transcription polymerase chain reaction(RT-PCR). Results The weight ratio of right ventricle to left ventricle plus septum[RV/(LV+S)] in model group was significantly higher than that in control group(P0.05).The plasma concen- tration of Apelin-36 protein in model group was significantly higher than that in control group(P