Enhanced alpha1-adrenergic trophic activity in pulmonary artery of hypoxic pulmonary hypertensive rats

Mechanisms that induce the excessive proliferation of vascular wall cells in hypoxic pulmonary hypertension (PH) are not fully understood. Alveolar hypoxia causes sympathoexcitation, and norepinephrine can stimulate alpha(1)-adrenoceptor (alpha(1)-AR)-dependent hypertrophy/hyperplasia of smooth muscle cells and adventitial fibroblasts. Adrenergic trophic activity is augmented in systemic arteries by injury and altered shear stress, which are key pathogenic stimuli in hypoxic PH, and contributes to neointimal formation and flow-mediated hypertrophic remodeling. Here we examined whether norepinephrine stimulates growth of the pulmonary artery (PA) and whether this is augmented in PH. PA from normoxic and hypoxic rats [9 days of 0.1 fraction of inspired O(2) (Fi(O(2)))] was studied in organ culture, where wall tension, Po(2), and Pco(2) were maintained at values present in normal and hypoxic PH rats. Norepinephrine treatment for 72 h increased DNA and protein content modestly in normoxic PA (+10%, P < 0.05). In hypoxic PA, these effects were augmented threefold (P < 0.05), and protein synthesis was increased 34-fold (P < 0.05). Inferior thoracic vena cava from normoxic or hypoxic rats was unaffected. Norepinephrine-induced growth in hypoxic PA was dose dependent, had efficacy greater than or equal to endothelin-1, required the presence of wall tension, and was inhibited by alpha(1A)-AR antagonist. In hypoxic pulmonary vasculature, alpha(1A)-AR was downregulated the least among alpha(1)-AR subtypes. These data demonstrate that norepinephrine has trophic activity in the PA that is augmented by PH. If evident in vivo in the pulmonary vasculature, adrenergic-induced growth may contribute to the vascular hyperplasia that participates in hypoxic PH.     

The role of transbronchial lung biopsy in the diagnosis of solitary pulmonary nodule

Transbronchial lung biopsy (TBLB) is a well-recognized diagnostic technique in diffuse interstitial lung diseases, but it is not considered to be the first choice in investigation of solitary pulmonary nodules (SPN). The main idea of this study was to increase the sensitivity of bronchoscopy using multiple techniques, especially TBLB, thus to avoid more aggressive diagnostic procedures. The objective of this prospective study was to evaluate the efficacy and safety of TBLB in the diagnosis of SPN, in comparison with other bronchoscopic techniques. Fifty patients with chest x-ray finding consistent with SPN underwent bronchoscopy with bronchial washing, brushing, bronchoalveolar lavage (BAL) and TBLB were included in this study. Thirty-one patients suffered from malignant tumors, while 19 patients had nonmalignant lesions. TBLB achieved overall diagnostic sensitivity of 62%, BAL of 29%, bronchial brushing of 16% and washing of 6%. Combining all techniques together, bronchoscopy had overall sensitivity of 86%. Concerning malignant lesions, TBLB had a sensitivity of 65%, specificity of 100%, and accuracy of 82%. TBLB had a significantly better yield for lesions with a diameter > or = 25 mm than for lesions of < 25 mm (sensitivity of 82% and 53% respectively, p < 0.05). Diagnostic yield improved significantly with the increasing number of specimens (less than 3 specimens: sensitivity 59%, 3 or more specimens: sensitivity 87%, p < 0.05). Complications of TBLB occurred in 2 (4%) patients: 1 incomplete pneumothorax and 1 hemorrhage. According to the results, we conclude that TBLB is an accurate and safe technique for the diagnosis of pulmonary solitary nodule with a diameter equal or greater than 25 mm.     

Vasorelaxing effect of U50,488H in pulmonary artery and underlying mechanism in rats

AIM: To investigate the relaxation effect and underlying mechanism of U50,488H (a selective kappa-opioid receptor agonist) in pulmonary artery in the rat. METHODS: Isolated pulmonary artery ring was perfused and the tension of the vessel was measured. RESULTS: U50,488H relaxed the pulmonary artery ring in a dose-dependent manner and the effect was abolished by nor-binaltorphimine, a selective kappa-opioid receptor antagonist. The relaxation effect of U50,488H in pulmonary artery was partially endothelium-dependent and was significantly attenuated in the presence of L-NAME. The relaxation effect of U50,488H was significantly attenuated by K(V) channel blocker 4-AP (4-aminopyridine), but not by glibenclamide (ATP-sensitive K+ channel blocker) nor TEA (tetraethylamonium, Ca2+-activated K+ channel blocker). Further study also showed that endothelium denudation and 4-AP have an additive inhibitory effect on pulmonary artery relaxation caused by U50,488H. CONCLUSION: Kappa-opioid receptor activation by U50,488H relaxes pulmonary artery via two separate pathways: one is endothelium-derived nitric oxide, the other is K(V) channel in pulmonary artery smooth muscle.     

Catheterization of pulmonary artery in rats with an ultraminiature catheter pressure transducer

Utilizing new materials and miniaturization techniques, an ultraminiature catheter pressure transducer for catheterization of the pulmonary artery (PA) has been developed and applied in intact, spontaneously breathing, anesthetized rats. The catheter arrangement consists of three components: 1) an SPR-671 ultraminiature pressure transducer (measuring catheter), 2) a plastic introducer (sheath) that is slipped over the measuring catheter, and 3) an external wire mounted on the outside of the introducer for bending its tip. The measuring catheter is first inserted through the right jugular vein into the right ventricle. The introducer is then slipped over it. The tip of the introducer is bent so that there is an angle of approximately 90 degrees or less to the shaft. The measuring catheter is advanced across the pulmonary valve into the PA. Measurements of pulmonary arterial pressure were made in five male Long Evans (364 +/- 7 g body wt) and five female Sprague-Dawley (244 +/- 7 g body wt) rats under control conditions. The effects of infusion of norepinephrine (0.1 mg.kg(-1).h(-1) iv for 20-min duration) were tested in Long Evans rats. Pulmonary arterial systolic pressure measurements were 34.0 +/- 0.8 and 29.5 +/- 0.4 mmHg, and diastolic pressure values were 23.6 +/- 0.8 and 18.1 +/- 0.6 mmHg in male Long Evans and female Sprague-Dawley rats, respectively. Norepinephrine induced an increase in pulmonary arterial systolic (40.8 +/- 0.1 mmHg) and diastolic (28.6 +/- 0.4 mmHg) pressures and an elevation in pulmonary vascular resistance from a control value of 0.093 +/- 0.003 to 0.103 +/- 0.004 mmHg.kg.min.ml(-1).     

内源性硫化氢对高肺血流大鼠肺动脉胶原含量的影响

目的：探讨内源性硫化氢（H2S）对大鼠高肺血流性肺血管结构重建的调节作用。方法：将32只雄性SD大鼠随机分为4组（n=8）：分流组、分流＋炔丙基甘氨酸（PPG组）、假手术组和假手术＋PPG组。对分流组和分流＋PPG组大鼠行腹主动脉-下腔静脉穿刺建立高肺血流动物模型。分流4周后,以敏感硫电极法测定肺组织H2S含量、以免疫组织化学法测定肺动脉胶原Ⅰ和胶原Ⅲ、基质金属蛋白酶-13（MMP-13）及其抑制物-1（TIMP-1）的表达。结果：分流4周后,大鼠肺组织H2S含量明显升高（P〈0.05） 应用PPG干预4周后,分流＋PPG组大鼠H2S含量明显降低 分流组大鼠与假手术组比较肺腺泡动脉胶原Ⅰ和胶原Ⅲ蛋白表达明显升高（P〈0.01）,分流＋PPG组大鼠肺动脉胶原Ⅰ和胶原Ⅲ蛋白表达与分流组相比进一步升高（P〈0.05） 分流＋PPG组大鼠肺动脉MMP-13、TIMP-1的蛋白表达及MMP-13/TIMP-1比值比分流组明显降低（P〈0.05）。结论：内源性H2S可能通过增加肺动脉壁胶原成分的降解、减少胶原含量而在高肺血流性肺动脉高压形成和肺血管结构重建中发挥保护性调节作用。     

Effect of L-arginine on pulmonary artery smooth muscle cell apoptosis in rats with hypoxic pulmonary vascular structural remodeling

This study investigated the effect of L-arginine (L-Arg) on the apoptosis of pulmonary arterysmooth muscle cells (PASMC) in rats with hypoxic pulmonary vascular structural remodeling,and itsmechanisms.Seventeen Wistar rats were randomly divided into a control group (n=5),a hypoxia group(n=7),and a hypoxia L-Arg group (n=5).The morphologic changes of lung tissues were observed underoptical microscope.Using the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling assay,the apoptosis of PASMC was examined.Fas expression in PASMC wasexamined using immunohistochemistry.The results showed that the percentage of muscularized artery insmall pulmonary vessels,and the relative medial thickness and relative medial area of the small and medianpulmonary muscularized arteries in the hypoxic group were all significantly increased.Pulmonary vascularstructural remodeling developed after hypoxia.Apoptotic smooth muscle cells of the small and median pul-monary arteries in the hypoxia group were significantly less than those in the control group.After 14 d ofhypoxia,Fas expression by smooth muscle cells of median and small pulmonary arteries was significantlyinhibited.L-Arg significantly inhibited hypoxic pulmonary vascular structural remodeling in association withan augmentation of apoptosis of smooth muscle cells as well as Fas expression in PASMC.These resultsshowed that L-Arg could play an important role in attenuating hypoxic pulmonary vascular structural remod-eling by upregulating Fas expression in PASMC,thus promoting the apoptosis of PASMC.     

Effects of endogenous carbon monoxide on collagen synthesis in pulmonary artery in rats under hypoxia

To study the role of endogenous carbon monoxide (CO) in collagen metabolism during hypoxic pulmonary vascular remodeling, a total of 18 Wistar rats were used in the study and they were randomly divided into three groups: hypoxia group (n = 6), hypoxia with zinc protoporphyrin-IX (ZnPP-IX) group (n = 6) and control group (n = 6). The measurement of mean pulmonary artery pressure (mPAP) and carboxyhemoglobin (HbCO) formation in lung tissue homogenates was measured. A morphometric analysis of pulmonary vessels was performed, in which the percentage of muscularized arteries (MA); partially muscularized arteries (PMA) and nonmuscularized arteries (NMV) in small and median pulmonary vessels, relative medial thickness (RMT) and relative medial area (RMA) of pulmonary arteries were analyzed. Collagen type I and III and transforming growth factor-beta3 (TGF-beta3) expressions were detected by immunohistochemical assay. The expressions of procollagen type I and III and TGF-beta3 mRNA were detected by in situ hybridization. The results showed that ZnPP-IX significantly increased mPAP and markedly decreased HbCO formation in lung tissue homogenates in rats under hypoxia (P < 0.01). In the hypoxia rats treated with ZnPP-IX, the percentage of muscularized arteries of small and median pulmonary vessels was obviously increased, and RMT and RMA of intra-acinar muscularized pulmonary arteries were markedly increased compared with hypoxic rats. Ultrastructural changes, such as hyperplasia and hypertrophy of endothelial cells (ECs) and smooth muscle cells (SMCs) and the increased number of SMCs in synthetic phenotype were found in intra-acinar pulmonary muscularized arteries of hypoxic rats treated with ZnPP-IX. Meanwhile, ZnPP-IX promoted the expression of collagen type I and III and TGF-beta3 protein in pulmonary arteries of rats under hypoxia (P < 0.01). Furthermore, ZnPP-IX elevated obviously the expressions of procollagen type I and III mRNA, and TGF-beta3 mRNA in pulmonary arteries of rats under hypoxia (P < 0.01). The results of this study suggested that ZnPP-IX played an important role in promoting collagen synthesis in pulmonary arteries of rats with hypoxic pulmonary structural remodeling by increasing the expression of TGF-beta3. The above findings also suggested a possible role of endogenous CO in the pathogenesis of chronic hypoxic pulmonary hypertension.     

Functional adaptation and remodeling of pulmonary artery in flow-induced pulmonary hypertension

Patients with left-to-right shunt congenital heart disease may develop pulmonary hypertension. Perioperative mortality of these patients is high due to abnormal vasoreactivity of the pulmonary artery (PA). We studied the changes in the PA induced by high pulmonary blood flow in rats with aortocaval fistula. Eight weeks after surgery, morphological changes of the PA were studied and vasomotor function was assessed by isometric force recording. Expression of endothelial nitric oxide (NO) synthase (eNOS), VEGF, and cyclooxygenase-2 (COX-2) proteins and levels of cGMP in the PA were analyzed. Rats with high pulmonary blood flow developed pulmonary hypertension, medial thickening, and increasing of internal elastic lamina and basement membrane in the PA. When compared with sham-operated animals, rats with fistula had significantly increased contractions in the PA, whereas relaxations to acetylcholine and NO donor were reduced. Concentrations of cGMP were reduced in the PA of rats with pulmonary hypertension (18.4 +/- 3.3 vs. 9.4 +/- 1.7 pmol/mg protein; P = 0.04). The altered vasomotor function was normalized by treatment with indomethacin. The PA of rats with fistula expressed higher levels of eNOS, phosphorylated eNOS, and COX-2. Sustained high PA blood flow in rats causes pulmonary hypertension that is morphologically and functionally identical with patients with flow-induced pulmonary hypertension. Abnormal vasomotor function of the PA in these animals appears to be mediated by reduced availability and the biological effect of endogenous NO and the high production of vasoconstrictor prostanoids. Increased eNOS and phosphorylated eNOS are most likely the adaptive changes in response to an increase in PA pressure secondary to high blood flow.     

Normal nomogram of the pulmonary artery

With the aim to establish quantitative characteristics of the pulmonary artery in order to use them in planning operations on congenital heart diseases, the data of morphometric investigations on the pulmonary artery has been studied in 83 hearts of newborns, children and mature persons died from causes not connected with any cardiovascular disorders. The regression equations are calculated; they reflect certain dependence between the quantitative characteristics of the pulmonary artery and the area of the body surface.     

Resveratrol downregulates acute pulmonary thromboembolism-induced pulmonary artery hypertension via p38 mitogen-activated protein kinase and monocyte chemoattractant protein-1 signaling in rats

AimsIn the present study, we explored the hypothesis that initiation of PH involves the upregulation of monocyte chemoattractant protein-1 (MCP-1) in acute PTE. We evaluated the effects of resveratrol and the role of p38 mitogen-activated protein kinase (MAPK) in this process.Main methodsA rat model of acute PTE was established by infusion of an autologous blood clot into the pulmonary artery through a polyethylene catheter. Rats were randomly divided into 1, 4, and 8 hour time groups. Resveratrol, C1142 (a rodent chimeric mAb that neutralizes rat MCP-1) or SB203580 (a p38MAPK specific inhibitor) was administered to the animals beginning 1 h prior to the start of the acute PTE protocol. At each time point, the mean pulmonary artery pressure (mPAP), mRNA and protein expressions of MCP-1 were measured. The phosphorylation of p38 MAPK (p-pMAPK) was also detected.Key findingsAcute PTE elicited significant increases in mean pulmonary artery pressure (mPAP), and up-regulated the expression of monocyte chemoattractant protein-1 (MCP-1) and phosphorylation of p38 mitogen-activated protein kinase (p-p38 MAPK). Administration of C1142 markedly reduced mPAP. Furthermore, pre-treatment of rats with resveratrol significantly reduced mPAP and down-regulated the expression of MCP-1, which was associated with robustly suppressed acute PTE-induced p-p38MAPK expression.SignificanceThese findings suggested that MCP-1 was involved in the formation of acute PTE-induced PH, and resveratrol down-regulated the expression of MCP-1 by inhibiting acute PTE-induced p-p38MAPK activation, which contributed to the decrease in PH.     

Targeted blocking of gene expression for CGRP receptors elevates pulmonary artery pressure in hypoxic rats

We previously described the protection by calcitonin gene-related peptide (CGRP) against hypoxic pulmonary hypertension. Here, we examine the roles of its putative receptor RDC-1 and receptor activity-modifying protein (RAMP) 1 in mediating this protection by selectively inhibiting their synthesis. RAMP1 is an accessory protein for another putative CGRP receptor, calcitonin receptor-like receptor. Antisense oligodeoxyribonucleotides (ASODNs, 5 mg.kg-1.day-1 or 5 and 10 mg.kg-1.day-1 for RDC-1) targeting RAMP1 and RDC-1 mRNAs were chronically infused to the pulmonary circulation of male Sprague-Dawley rats during 7 days of normoxia or hypobaric hypoxia (380 mmHg), and alpha-CGRP ASODN was used as a technical control. CGRP, RAMP1, and RDC-1 ASODNs significantly elevated pulmonary artery pressure (PPA) in chronic hypoxic rats compared with hypoxic mismatched ASODN (MMODN) and saline vehicle controls. CGRP and RAMP1 ASODNs raised PPA in normoxic rats briefly exposed to 10% O2 above MMODN and saline controls. Moreover, normoxic rats treated with CGRP ASODN had higher basal pulmonary vascular tone compared with controls. These data confirm the protective role of CGRP in the pulmonary circulation and suggest that endogenous RAMP1 and RDC-1 are essential in regulation of PPA in hypoxia. This is the first in vivo evidence supporting RDC-1 and RAMP1 as functional CGRP receptor and receptor component.     

慢性低O2高CO2肺动脉高压大鼠肺动脉尾加压素Ⅱ受体的动态变化

目的:探讨尾加压素Ⅱ受体(urotensinⅡreceptor,UT)在慢性低氧高二氧化碳肺动脉高压大鼠肺动脉中的动态变化及其意义.方法:对不同低氧(高二氧化碳)时间(1周、2周、4周)大鼠,放射性配基结合法检测肺动脉质膜UT结合位点,组织原位杂交测定各级肺小动脉UT及尾加压素Ⅱ(UⅡ)mRNA的表达.结果:①肺动脉平均压(mPAP)、右心室(RV)和左心室加室间隔(LV S)的重量比:1周组(1HH)较对照组(NC)分别增高26.2%和21.6%、2周组(2HH)较1HH增高22.5%和14.1%、4HH组与2HH组间无显著差别(P＞0.05).②肺主动脉质膜UT最大结合位点(Bmax),1HH组比NC组高38.8%(P＜0.01),2HH组比1HH组高23.2%(P＜0.01),4HH组比2HH组高7.3%(P＜0.05),随低氧时间延长有渐升的趋势;UⅡ受体亲和力(Kd值)各组间无差别.③三级肺小动脉UⅡmRNA相对含量的变化:2HH、4HH组明显高于NC组(P均＜0.01);2HH组较1HH组分别高5.9%(P＞0.05)、16.4%和9.1%(P均＜0.01);4HH组与2HH组间无明显差异.④三级肺小动脉UT mRNA相对含量的变化:各低氧高二氧化碳组均高于NC组(P均＜0.01),以1HH组后2级肺小动脉的表达最强,而4HH组与2HH组间无显著差别(P＞0.05).⑤肺小动脉显微结构的变化:4HH组各级血管均有显著重构,1HH组无明显变化,2HH组介于两者之间.结论:UT在慢性低氧高二氧化碳肺动脉高压大鼠肺动脉内的动态变化与肺动脉高压、肺血管改建的病理进程密切相关.     

Distribution of the pulmonary artery and vein in the chimpanzee lung

Lungs of two chimpanzees (Pan troglodytes) were examined. The right pulmonary artery runs across the ventral side of the right upper lobe bronchiole and, then across the dorsal side of the right middle lobe bronchiole. Thereafter, it runs between the dorsal bronchiole system and the lateral bronchiole system, along the right bronchus. During its course, it gives off arterial branches which run along each bronchiole. The left pulmonary artery runs across the dorsal side of the left middle lobe bronchiole and then between the dorsal bronchiole system and the lateral bronchiole system. The branches of the pulmonary artery run mainly along the dorsal or lateral side of the bronchiole. The pulmonary veins run mainly along the ventral or medial side of the bronchioles, and between them. Finally, they enter the left atrium with four large veins, i.e. the common trunk of the right upper lobe vein and the right middle lobe vein, right lower lobe pulmonary venous trunk, left middle lobe vein, and left lower lobe pulmonary venous trunk.     

Right and left ventricular function after chronic pulmonary artery banding in rats assessed with biventricular pressure-volume loops

In many patients with congenital heart disease, the right ventricle (RV) is subjected to abnormal loading conditions. To better understand the state of compensated RV hypertrophy, which could eventually progress to decompensation, we studied the effects of RV pressure overload in rats. In the present study, we report the biventricular adaptation to 6 wk of pulmonary artery banding (PAB). PAB resulted in an RV pressure overload to approximately 60% of systemic level and a twofold increase in RV mass (P < 0.01). Systemic hemodynamic parameters were not altered, and overt signs of heart failure were absent. Load-independent measures of ventricular function (end-systolic pressure-volume relation, preload recruitable stroke work relation, maximum first time derivative of pressure divided by end-diastolic volume), assessed by means of pressure-volume (PV) loops, demonstrated a two- to threefold increase in RV contractility under baseline conditions in PAB rats. RV contractility increased in response to dobutamine stimulation (2.5 microg.kg(-1).min(-1)) both in PAB and sham-operated rats in a similar fashion, indicating preserved RV contractile reserve in PAB rats. Left ventricular (LV) contractility at baseline was unaffected in PAB rats, although LV volume in PAB rats was slightly decreased. LV contractility increased in response to dobutamine (2.5 microg.kg(-1).min(-1)), both in PAB and sham rats, whereas the response to a higher dose of dobutamine (5 microg.kg(-1).min(-1)) was blunted in PAB rats. RV pressure overload (6 wk) in rats resulted in a state of compensated RV hypertrophy with preserved RV contractile reserve, whereas LV contractile state at baseline was not affected. Furthermore, this study demonstrates the feasibility of performing biventricular PV-loop measurements in rats.