Pulmonary artery remodeling and pulmonary hypertension after exposure to hyperoxia for 7 days. A morphometric and hemodynamic study.

This study shows by morphometric and hemodynamic techniques that exposure to hyperoxia at normobaric pressure causes rapid structural remodeling of rat pulmonary arteries and pulmonary hypertension. After 7 days of 90% O2, pulmonary artery cross-sectional area is reduced by a striking loss of intraacinar arteries (control, 13 +/- 1 sq mm; exposed, 8 +/- 1 sq mm; P less than 0.001), the ratio of arteries to alveoli being 4:100 in control rats and 2.5:100 after hyperoxia. The lumen of preacinar and intraacinar arteries is narrowed by a reduction of vessel external diameter (ED) and an increased medial wall thickness (MT). There is a significant reduction in the percent medial thickness [( 2 X 100 X MT]/ED) in both regions. The proportion of muscular and partially muscular intraacinar arteries increases at the expense of nonmuscular ones (P [chi 2] less than 0.01), and fully muscular arteries appear in the alveolar wall where they are not normally found. Intimal thickening occurs in 19% of alveolar duct and 34% of alveolar wall nonmuscular arteries. Right ventricular hypertrophy occurs, the ratio of the left ventricle plus the septum to the right ventricle being significantly reduced (control, 4.07 +/- 0.26; exposed, 3.23 +/- 0.10; P less than 0.02). After 3 days of 87% O2, pulmonary artery pressure is still normal (17.0 +/- 0.9 mmHg) but after 7 days it is significantly increased (26.2 +/- 0.9 mmHg; P less than 0.01), as is pulmonary vascular resistance (control, 0.033 +/- 0.003; exposed, 0.065 +/- 0.015 U/kg; P less than 0.05). Return to air breathing (after 7 days at 87% O2) causes pulmonary vasoconstriction and a further rise of the pulmonary artery pressure (to 38.3 +/- 3.3 mmHg after 60 minutes).     

Hypoxia and incorporation of 3H-thymidine by cells of the rat pulmonary arteries and alveolar wall.

In the pulmonary arterial circulation hypoxia produces increase in thickness of the medial muscle coat as well as of the adventitia; in addition muscle appears in smaller arteries than is normal and the number of small arteries that fill on Micropaque-gelatin injection is reduced. To assess the role of hyperplasia in these changes, the uptake of 3H-thymidine by the cells of the pulmonary arterial wall has been studied in rats exposed to hypobaric hypoxia (exposure to 380 torr) after 1, 3, 5, 7, 10, and 14 days. Using autoradiographs of 1-micron sections, the glutaraldehyde-distended intrapulmonary hilar muscular artery, the peripheral, intraacinar arteries less than 100 micron in external diameter, and the alveolar wall had different patterns of uptake. In the hilar pulmonary artery, after 24 hours of exposure, the labeling index for adventitial fibroblasts is increased eightfold over the control value, and for endothelial cells, threefold, while for medial smooth muscle cells, there is a gradual and small increase to Day 14. Newly muscularized intraacinar arteries are first apparent at Day 3, when they comprise 40% of the intraacinar arteries, increasing to 80% at Day 7. No decrease in density of arteries is found. Uptake of 3H-thymidine by new muscle cells is not apparent until Day 5 when labeling is maximum. The endothelial cells of the newly muscularized arteries show an increased labeling index only at Days 7 and 10. The veins and normally muscular arteries do not show these changes. In the alveolar walls, the concentration of labeled cells is significantly above the control value at Days 3, 5, and 7 and significantly below, at Day 14. At this level, the interstitial, epithelial, and endothelial cells contribute to the increase.     

Injury and remodeling of pulmonary veins by high oxygen. A morphometric study.

Breathing 87% oxygen at normobaric pressure for 28 days injuries and remodels the wall of distal pulmonary veins (less than or equal to 150 mu). Occluded vessels are evident, as are vessel remnants in which wall integrity is lost (obliterated vessels). Significantly more veins have a muscular or partially muscular wall than normal (P less than or equal to 0.001 for veins in each size category less than or equal to 150 mu, chi-square test). In some veins new muscle develops between an external and internal lamina but in many it develops within the intima, beneath the endothelium and adluminal to a single lamina. Small veins (20-25 mu in ED) with a muscular or partially muscular wall are present only in the hyperoxic lung. Increase in the percent medial thickness (%MT) of veins indicates lumen narrowing: this is relatively greater in the smallest veins. Reduction in the cross-sectional area of venous segments that are immediately postcapillary, by lumen narrowing or occlusion, contributes to the restriction of the pulmonary vascular bed by hyperoxia.     

Pulmonary artery structural changes in two colonies of rats with different sensitivity to chronic hypoxia.

Chronic hypoxia causes more severe pulmonary hypertension in the Hilltop colony of Sprague-Dawley rats than in the Madison colony and also greater polycythemia and vasoconstriction. This study examines the structural features of the pulmonary artery bed, another contributing factor to hypoxic hypertension. After 14 days of hypobaric hypoxia, in Hilltop rats, more of the intraacinar arteries became muscular, and the medial thickness of intraacinar and preacinar arteries was greater. In Hilltop control rats, muscle was found in more intraacinar arteries, but, paradoxically, acute hypoxic vasoconstriction was less. Thus, while in chronic hypoxia increased muscle correlates with pulmonary hypertension, in control rats the reserve seems to be true. The increased muscle in control Hilltop rats could, however, predispose to the greater muscularization seen after chronic hypoxia.     

Rat pulmonary artery restructuring and pulmonary hypertension induced by continuous Escherichia coli endotoxin infusion

We have studied the effect of continuous endotoxin infusion on rat pulmonary structure and function (69.4 ng/100 gm body weight/min for 24 hours). After 6 days of endotoxin infusion, lack of filling of pre- and intraacinar arteries was evident on pulmonary arteriograms. Microscopy demonstrated lumen narrowing in preacinar arteries and occlusion of intraacinar arteries. Morphometry of patent intraacinar arteries established dilation and increased wall muscle. Widespread alveolar wall injury was evident. After 24 hours of infusion, pulmonary artery pressure was raised (delta 9 mmHg; p less than or equal to 0.001); it then fell but was again increased by day 6 (delta 6 mmHg; p less than or equal to 0.05). Pulmonary vascular resistance was markedly increased at 24 hours (day 0 = 0.1 +/- 0.011 dyne/sec/cm-5; 24 hours endotoxin = 0.572 +/- 0.102 dyne/sec/cm-5; p less than or equal to 0.02). It remained elevated during the infusion period but was not significant. At day 6 the alveolar-arterial oxygen diffusion gradient (A-aDO2) was increased (day 0 = 19.6 +/- 1.39 mmHg, day 6 endotoxin = 33.8 +/- 0.1 mmHg; p less than or equal to 0.001). The arterial oxygen tension (PaO2) was decreased (day 0 = 86.5 +/- 1.8 mmHg, day 6 endotoxin = 74 +/- 2.52 mmHg; p less than or equal to 0.05), as was the arterial carbon dioxide tension (PaCO2) (day 0 = 36.0 +/- 0.73 mmHg, day 6 endotoxin = 30 +/- 1.9 mmHg; p less than or equal to 0.05). Thrombocytopenia occurred during the first 72 hours of infusion (day 0 = 7.41 +/- 0.41 X 10(5)/mm3, day 1 endotoxin = 2.43 +/- 0.30 X 10(5)/mm3, day 3 endotoxin = 2.32 +/- 0.31 X 10(5)/mm3; p less than or equal to 0.001) but by day 6 the platelet count had returned to basal levels (9.9 +/- 0.65 X 10(5)/mm3). Endotoxin increased the number of leukocytes in peripheral blood (day 0 = 12.8 +/- 1.2 X 10(3)/mm3, day 3 endotoxin = 17.0 +/- 1.86 X 10(3)/mm3, day 6 endotoxin = 22.5 +/- 1.8 X 10(3)/mm3; p less than or equal to 0.01 for day 6). Plasma concentrations of 6-keto-prostaglandin F1 alpha decreased during the first 24 hours of infusion (day 0 = 0.56 +/- 0.076 ng/ml, 24 hours endotoxin = 0.27 +/- 0.026 ng/ml; p less than or equal to 0.05) and thromboxane (TX) B2 in the first 15 hours (day 0 = 0.23 +/- 0.058 ng/ml, 15 hours endotoxin = 0.09 +/- 0.14 ng/ml; p less than or equal to 0.05).(ABSTRACT TRUNCATED AT 400 WORDS)     

Lung lymphatics increase after hyperoxic injury. An ultrastructural study of casts.

The microscopic lymphatics of the lung can be cast and studied with scanning electron microscopy. This technique shows several different forms of lymphatics and the interstitial space that leads into lymphatics as no other method can. To study changes in lymphatic forms, rats were placed in 85% oxygen for 7 days to produce pulmonary edema. Methyl methacrylate resin was injected into the lung vasculature at various times after the animals were removed from hyperoxia. In the animals not exposed to hyperoxia, no artery, vein, or airway was surrounded by a lymphatic cast. However, in rats that were in the hyperoxic chamber, 22% of arteries, 30% of veins, and 51% of indeterminate blood vessels (which could be arteries or veins) were encompassed by saccular lymphatic casts. These lymphatics were still observed 7 days after recovery from hyperoxia. Fourteen days after hyperoxia, the lymphatics returned to control values. Only 9% of the pleural surface of the animals not exposed to hyperoxia had initial lymphatics. Fifty-two percent of the hyperoxia-exposed animals had initial lymphatics, measured 3 days after exposure. This decreased to 14% 14 days after exposure to hyperoxia (P < 0.01). Conduit lymphatics were found on the pleural surfaces of 33% of animals exposed to ambient air and 100% of animals exposed to the high-oxygen environment (P < 0.05). The median percentage of the pleural surface covered with lymphatics was 0 in the animals exposed to ambient air. It was 65% in animals exposed to hyperoxia, 3 days after returning to room air. It was again 0 in animals exposed to hyperoxia, 14 days after returning to room air (P < 0.001). The lymphatics around veins expanded more than around arteries (P < 0.0001). These results indicate that in the rat all compartments of the lung lymphatics expand after the injury and edema caused by oxygen and return to normal with the resolution of the edema.     

Ultrastructural changes in intraacinar pulmonary veins. Relationship to 3-methylindole-induced acute pulmonary edema and pulmonary arterial changes in cattle.

In 3-methylindole (3MI)-treated cattle electron-microscopic examination of intrapulmonary arteries showed changes of an arteritis which could be related to pulmonary hypertension. To further elaborate on this concept, the present study describes the ultrastructural pathology of intraacinar pulmonary veins in cattle 72 hours after oral administration of 3MI. The changes include significant thickening of the muscular pads of the media, massive glycogen accumulation in the venous smooth muscle cells, proliferation of the myointimal cells, focal protrusion of cytoplasmic portion of a smooth muscle cell into an adjacent cell body suggestive of vasoconstriction and emigration of lymphocytes and platelets through the vascular wall. The experimental data are discussed in relation to the ultrastructural pathology of intraacinar pulmonary arteries and acute pulmonary edema. The authors further present evidence that 3MI acute pneumotoxicosis is also associated with drastic vascular changes which may signify sudden elevation in arterial and venous pressures in the pulmonary system of cattle.     

Transgenic overexpression of granulocyte macrophage-colony stimulating factor in the lung prevents hyperoxic lung injury

Granulocyte macrophage-colony stimulating factor (GM-CSF) plays an important role in pulmonary homeostasis, with effects on both alveolar macrophages and alveolar epithelial cells. We hypothesized that overexpression of GM-CSF in the lung would protect mice from hyperoxic lung injury by limiting alveolar epithelial cell injury. Wild-type C57BL/6 mice and mutant mice in which GM-CSF was overexpressed in the lung under control of the SP-C promoter (SP-C-GM mice) were placed in >95% oxygen. Within 6 days, 100% of the wild-type mice had died, while 70% of the SP-C-GM mice remained alive after 10 days in hyperoxia. Histological assessment of the lungs at day 4 revealed less disruption of the alveolar wall in SP-C-GM mice compared to wild-type mice. The concentration of albumin in bronchoalveolar lavage fluid after 4 days in hyperoxia was significantly lower in SP-C-GM mice than in wild-type mice, indicating preservation of alveolar epithelial barrier properties in the SP-C-GM mice. Alveolar fluid clearance was preserved in SP-C-GM mice in hyperoxia, but decreased significantly in hyperoxia-exposed wild-type mice. Staining of lung tissue for caspase 3 demonstrated increased apoptosis in alveolar wall cells in wild-type mice in hyperoxia compared to mice in room air. In contrast, SP-C-GM mice exposed to hyperoxia demonstrated only modest increase in alveolar wall apoptosis compared to room air. Systemic treatment with GM-CSF (9 micro g/kg/day) during 4 days of hyperoxic exposure resulted in decreased apoptosis in the lungs compared to placebo. In studies using isolated murine type II alveolar epithelial cells, treatment with GM-CSF greatly reduced apoptosis in response to suspension culture. In conclusion, overexpression of GM-CSF enhances survival of mice in hyperoxia; this effect may be explained by preservation of alveolar epithelial barrier function and fluid clearance, at least in part because of reduction in hyperoxia-induced apoptosis of cells in the alveolar wall.     

Rat pulmonary circulation after chronic hypoxia: hemodynamic and structural features.

In 55 Sprague-Dawley rats (mean wt, 277 +/- 6.2 g) exposed to hypobaric hypoxia (air at 380 mmHg), and 23 weight-matched controls kept in room air, pulmonary and systemic artery pressures were measured daily for 2 wk via indwelling catheters. After each day of exposure, 1 or 2 hypoxic rats, to a total of 20, and 5 control rats were killed during the experiment. In these rats, the pulmonary arterial tree was injected post mortem with barium-gelatin and inflated with formaldehyde solution, and three structural features were quantified microscopically: 1) abnormal extension of muscle into peripheral arteries where it is not normally present (EMPA); 2) increased wall thickness of the normally muscular arteries, expressed as a percentage of external diameter (%WT); and 3) reduction in artery number expressed as an increase in the ratio of alveoli to arteries (A/a). Mean pulmonary artery pressure (Ppa) rose significantly after day 3 of hypoxic exposure (P less than 0.05) and had doubled by day 14; the mean systemic artery pressure (Psa) of hypoxic rats and Ppa and Psa of control rats were unchanged. The level of Ppa correlated with the degree of structural changes; for EMPA, r = 0.84; for %WT, r = 0.64; and for A/a, r = 0.73 (P less than 0.001 in all.     

Hyperoxia potentiates Ureaplasma urealyticum pneumonia in newborn mice.

The effect of continuous exposure to 80% oxygen on newborn mice with Ureaplasma urealyticum pneumonia was determined. Mice were inoculated intranasally with either U. urealyticum or sterile broth and then housed in either 80% oxygen or room air (21% oxygen). The mice were sacrificed at either 7 or 14 days after inoculation. Significantly more mice in the U. urealyticum group housed in 80% O2 than in the room air-exposed group were culture positive 14 days after inoculation (P = 0.042), but no difference was found at 7 days. The presence of alveolar macrophages, neutrophils, and lymphocytes and alveolar wall thickness were determined. Overall, the group housed in 80% O2 and inoculated with U. urealyticum had severe pulmonary lesions at both time points, while the lesion severity in the room air-exposed group inoculated with U. urealyticum and the group housed in 80% O2 and inoculated with sterile broth was dependent on the time point. Mortality was significantly higher in the group housed in 80% O2 and inoculated with U. urealyticum than it was in all other groups (P less than 0.001). Our results indicate that hyperoxia causes the persistence of U. urealyticum in the lungs of newborn mice, acutely potentiates the inflammatory response, and turns an otherwise self-limited pneumonia into a lethal disease.     

Human postnatal pulmonary arterial remodeling. Ultrastructural studies of smooth muscle cell and connective tissue maturation

A quantitative light and electron microscopic study of the elastic conducting, small muscular resistance arteries (accompanying or just proximal to the terminal bronchioli) and respiratory unit pulmonary arteries was carried out on the autopsy specimens of 12 children (newborn to 2 years) and three adults, who died without cardiopulmonary disease. Between birth and 1 month, in muscular and respiratory unit arteries, wall thickness decreased due to a reduction in mean smooth muscle cell diameter (p less than 0.01) and a reduction in overlap between adjacent cells. In the elastic arteries, the distance between adjacent elastic lamellae decreased as smooth muscle cell diameter decreased (p less than 0.01 for both). At birth, smooth muscle cells appeared immature, synthetic rather than contractile organelles predominating. Smooth muscle cell filament (thick, thin, and intermediate) volume density increased by 12 to 13% by 6 months in the small muscular arteries and by 2 years in the elastic arteries (p less than 0.001 for both). Surface and cytoplasmic dense bodies increased in a similar manner (p less than 0.001). The findings indicate a postnatal increase in contractile myofilament and surface dense bodies. The amount of connective tissue in the subendothelium and media increased between 1 month and adulthood, collagen finally predominating in small muscular arteries and elastin in the conducting arteries. Collagen fibrils showed regional differences in size within the media, between media and adventitia, and between different types of artery, and increased in size with age (p less than 0.001). Thus, the intrapulmonary arteries from hilum to precapillary bed adapted structurally to extrauterine life. It is suggested that the high fetal pulmonary vascular resistance is due to the shape and arrangement of smooth muscle cells within the vessel wall, rather than to an excessive contractility of each cell. After 1 month, remodeling occurred more slowly with growth, involving an increase in wall thickness, connective tissue deposition, and smooth muscle cell maturation.     

Comparison of sleep-disordered breathing among healthy elderly in the seventh, eighth, and ninth decades of life

We investigated the prevalence of sleep-disordered breathing (SDB) in healthy 80 year-old subjects (n = 38) as compared with healthy 70-(n = 33) and 60-year-old subjects (n = 34). The apnea-hypopnea index (AHI) increased significantly across decades: 39.5% (15 of 38) of 80 year olds, 33.3% (11 of 33) of 70 year olds, and 2.9% (1 of 34) of 60 year olds had an AHI greater than or equal to 5 (chi 2 = 14.0, p less than 0.001). The prevalence of SDB as measured by a more stringent apnea index criterion of greater than or equal to 5 was 18.9% of those in their 80s, 12.1% in their 70s, and 0% in their 60s (chi 2 = 6.63, p less than 0.05). Significant gender differences were noted in the proportion of subjects with AHI greater than or equal to 10: 22.4% of men versus 5.4% of women (chi 2 = 4.25, p less than 0.05). These data suggest that SDB increases with advancing age even in the healthy elderly and may be more marked in healthy men than women.     

Effect of He-O2 breathing on blood gases and ventilation during exercise in normal man

Temporal changes in ventilation (VI) and arterial blood gases after substitution of helium (He) for nitrogen were studied in normal man during constant load exercises of 14 min duration (30 and 90 W). An abrupt switch of helium for air breathing (protocol 1; 5 subjects), or vice-versa (protocol 2; 4 subjects), was made at the 7th min. Whatever the work loads, the effect of He appeared rapidly: higher values of VI (protocol 1) were observed throughout the 7 min period of He-O2 breathing, but were only significant (p less than or equal to 0.05) during the first minute after substitution at 90 W. Reverse pattern was observed in protocol 2. Helium induced alveolar hyperventilation: sustained and significant hypocapnia (p less than or equal to 0.05) was observed during helium breathing. This effect does not seem to be a consequence of pulmonary gas exchange disturbance, in that concomitant Po2 was normal. It is suggested that He could have evoked a reflex which overrode humoral regulation. Significant increase in ventilatory CO2 responses at rest during He-O2 compared to air breathing in seven subjects (p less than or equal to 0.01) seems to confirm this hypothesis.     

Constrictive and restrictive pulmonary hypertension in the newborn and infant

The normal pulmonary circulation is constricted at birth and, as judged by its low arterial density, is relatively more restricted than in the older infant and child. During adaptation to air breathing, pulmonary arterial dilatation occurs rapidly, but also the compliance of the resistance arterial segment increases. In the fetus and newborn, the resistance segment is proximal to the respiratory or alveolar surface. Further expansion of the pulmonary vascular bed occurs by growth in size of lumen diameter of existing arteries and growth of new ones. Multiplication of alveoli and arteries is relatively dissociated--alveolar density can increase normally without normal vascular multiplication. Persistent pulmonary hypertension of the newborn occurs because of (1) lung hypoplasia associated with hypoplasia of the vascular bed, usually affecting both size and number of units, (2) abnormal muscularization of intraacinar arteries before birth, causing restriction of vascular volume, (3) failure of the adaptation programs, and (4) hyperreactivity. Immaturity of the circulation is apparent as hyperreactivity or "twitchiness": this can be superimposed on each of the other types. A hyperirritable vascular bed can cause a labile and then a fixed pulmonary hypertension that does not respond to dilators.     

The effect of heparin on the haemodynamic and structural response in the rat to acute and chronic hypoxia

In the mouse, heparin administered intermittently, has been shown to reduce the right ventricular hypertrophy (RVH) caused by hypoxia. We have investigated in the rat the effect of heparin on the haemodynamic and pulmonary vascular structural remodelling produced by hypoxia, with special reference to the new muscularization of peripheral arteries. Heparin at one of two doses (30 and 50 u/kg/h) was administered by continuous intravenous infusion from a miniosmotic pump to rats during 10 days exposure to hypobaric hypoxia and its effect examined on mean pulmonary artery pressure (PPa), RVH and, using morphometric techniques, vascular structural remodelling. Hypoxia produced the haemodynamic and structural changes previously described in this model. Heparin had no significant effect on PPa; a slight reduction in RVH was seen in the high-dose heparin group. After heparin, the narrowing of the axial pulmonary artery lumen caused by hypoxia was less: heparin reduced the proportion of arteries that became muscularized, particularly at alveolar duct level where the pericyte is the precursor smooth muscle cell. Heparin did not diminish the increase in medial thickness or reduction in external diameter of muscular arteries. Some rats, after chronic hypoxia, did not respond to an acute hypoxic challenge yet were no different from 'responders' in other haemodynamic and structural features. Including all rats, the mean acute pressor response to hypoxia was unaffected by heparin: taking only responder rats, a trend was apparent that heparin reduced the rise in PPa on acute hypoxic challenge.     

内膜新生性肺血管重构肺动脉高压大鼠模型的建立及评价

背景：目前尚缺乏简单易行、实用、操作性强的血管内膜新生性肺血管重构肺动脉高压动物模型。 目的：建立内膜新生性肺血管重构大鼠肺动脉高压模型。 方法：40只雄性SD大鼠随机分为2组：M+P组(n=26)大鼠行左肺切除,2周后皮下注射野百合碱60 mg/kg;对照组(n=14)大鼠仅行假手术处理。于术后5周检测肺动脉压、右心室/(左心室+室间隔)质量的比值,同时观察右肺动脉病理形态学改变。以光镜下每1 mm²面积内Ⅷ因子标记阳性的直径小于100 μm的肺血管数评价肺内微血管密度。 结果与结论：M+P组大鼠存活率85%(22/26),对照组存活率为100%(14/14)。与对照组相比,M+P组大鼠肺动脉压力和右心室/(左心室+室间隔)质量的比值明显增高(P < 0.01);与对照组相比,M+P组大鼠肺内直径为50-100 μm和100-150 μm的肌型小动脉中膜相对厚度均显著增加(P < 0.01),肺内微血管密度显著减少(P < 0.01)。光镜显示M+P组大鼠注射野百合碱后5周肌型肺小动脉中膜明显增厚,肺腺泡内小动脉明显肌化、内膜增厚。对照组大鼠肺小动脉未见血管结构重建。实验成功建立了内膜新生性肺血管重构大鼠肺动脉高压模型,操作相时简便,动物死亡率较低。     

Bronchiolar Remodeling in Adult Mice Following Neonatal Exposure to Hyperoxia: Relation to Growth

Preterm infants who receive supplemental oxygen for prolonged periods are at increased risk of impaired lung function later in life. This suggests that neonatal hyperoxia induces persistent changes in small conducting airways (bronchioles). Although the effects of neonatal hyperoxia on alveolarization are well documented, little is known about its effects on developing bronchioles. We hypothesized that neonatal hyperoxia would remodel the bronchiolar walls, contributing to altered lung function in adulthood. We studied three groups of mice (C57BL/6J) to postnatal day 56 (P56; adulthood) when they either underwent lung function testing or necropsy for histological analysis of the bronchiolar wall. One group inhaled 65% O₂ from birth until P7, after which they breathed room air; this group experienced growth restriction (HE+GR group). We also used a group in which hyperoxia‐induced GR was prevented by dam rotation (HE group). A control group inhaled room air from birth. At P56, the bronchiolar epithelium of HE mice contained fewer Clara cells and more ciliated cells, and the bronchiolar wall contained ～25% less collagen than controls; in HE+GR mice the bronchiolar walls had ～13% more collagen than controls. Male HE and HE+GR mice had significantly thicker bronchiolar epithelium than control males and altered lung function (HE males: greater dynamic compliance; HE+GR males: lower dynamic compliance). We conclude that neonatal hyperoxia remodels the bronchiolar wall and, in adult males, affects lung function, but effects are altered by concomitant growth restriction. Our findings may partly explain the reports of poor lung function in ex‐preterm children and adults. Anat Rec, 297:758–769, 2014. © 2014 Wiley Periodicals, Inc.     

Rat pulmonary artery wall injury by chronic intermittent infusions of Escherichia coli endotoxin. Obliterative vasculitis and vascular occlusion

To examine the effect of intermittent endotoxemia on rat pulmonary artery structure and hemodynamic function we infused purified Escherichia coli endotoxin on four occasions over 3 weeks (at 7-day intervals), through an indwelling catheter placed in the external jugular vein. The fourth infusion of endotoxin was associated with widespread but focal alveolar consolidation, reduced perfusion of small pulmonary arteries by lumen occlusion and obliteration, pulmonary vascular wall injury, and a peripheral leukocytosis (mean +/- SEM total leukocytes, endotoxin 133.5 +/- 23 X 10 mm3, control 12.2 +/- 1.2 X 10 mm3, p less than 0.001) in which polymorphonuclear (PMN) leukocytes predominated at the expense of lymphocytes (p2x less than 0.01). The alveolar wall was thickened and the alveolar space was consolidated by degenerating polymorphonuclear leukocytes, mononuclear cells, lipid laden alveolar macrophages, erythrocytes, fibrin, and cell debris. In regions of alveolar consolidation vessel lumens were either narrowed by subendothelial cell collections that consisted either of mononuclear cells or degenerating mural and inflammatory cells, or they were occluded by degenerating inflammatory cells and cell debris. The walls of occluded vessels were evident only by their residual elastic laminae: remnants of lysed endothelial cells lined the intima and the media consisted of degenerating mural and inflammatory cells. Capillary endothelial cells showed extensive hydropic degeneration and lysis of cell contents. Intimal precursor smooth muscle cells were hypertrophied but were not associated with the appearance of mature smooth muscle cells in the walls of small pulmonary arteries. In regions of less severe alveolar consolidation by inflammatory cells, vessel wall injury was still evident but less marked; precursor smooth muscle cells were hypertrophied; subepithelial and subendothelial collections of fluid and fibrin were present; and plasma membranes of endothelial cells were disrupted. Despite extensive pulmonary vascular injury, chronic intermittent endotoxemia did not produce the structural changes associated with pulmonary hypertension (medial thickening and appearance of medial muscle in previously nonmuscular arteries) nor a significant change in pulmonary artery pressure.     

先天性心脏病伴肺动脉高压肺组织中腺泡内动脉转化生长因子-β1 mRNA和内皮素-1 mRNA的表达及意义

目的探讨转化生长因子-β1(TGF-β1)和内皮素-1(ET-1)在先天性心脏病(先心病)伴肺动脉高压(PH)的肺组织腺泡内肺动脉中的表达及意义.方法收集51例肺组织,其中41例为左向右分流型先心病患儿[伴PH 25例(A组),无PH 16例(B组)],对照组10例(C组),应用原位杂交、图像分析检测51例腺泡内肺动脉(IAPA)TGF-β1 mRNA和ET-1 mRNA的表达及平均吸光度值(A值);透射电镜观察肺组织超微结构;弹力纤维(VG)染色显示腺泡内肺动脉并计算其数量的变化.结果 (1)肺腺泡内部分肌型及环肌型动脉的数量,A、B两组分别与C组比较, F值分别为149.96、142.01,P<0.01;(2)电镜观察,有的肺小动脉内皮细胞增生;中膜平滑肌增厚,平滑肌细胞面积增大;外膜胶原纤维密集;毛细血管基膜增厚;(3)原位杂交发现,TGF-β1 mRNA在A、B两组腺泡内肺动脉均有阳性表达,A值分别为(0.1988±0.0498)、(0.1098±0.0428),C组表达微弱(A值=0.0578±0.0096),A、B、C三组间比较差异有统计学意义(P<0.05);ET-1 mRNA 在A、B两组肺腺泡内肺动脉内皮细胞表达明显增强,A值分别为(0.1692±0.0205)、(0.1004±0.0140),C组仅有微弱表达(A值=0.0746±0.0119),A、B、C三组间比较差异有统计学意义(P<0.01).结论左向右分流型先心病患儿肺组织腺泡内部分肌型及肌型动脉数量明显增加,肺血管结构重组,TGF-β1 mRNA、ET-1 mRNA表达增高与先心病伴PH的发生有关系.     

Rat lung alveolar type I epithelial cell injury and response to hyperoxia.

Hyperoxia has been shown to cause extensive lung injury, which involves all components of the alveolar septum, although the type I epithelium has generally been reported to be resistant to significant injury. Electron microscopic morphometry was performed to define changes in volumes of subcellular components of alveolar epithelial cells in rats exposed to 85% O2 for 0, 7, and 14 d. Because of their large size, type I cells in control animals actually contain a greater volume of most of the organelles involved in cell metabolism than do type II cells. Hyperoxic exposure causes a dramatic change in the subcellular composition of the average type I cell, suggesting significant injury and/or response. Injury was suggested by the finding that lysosomes plus peroxisomes increased 1,250% after 7 d in hyperoxia and remained elevated by 200% after 14 d of exposure. Volumes of mitochondria, rough endoplasmic reticulum, smooth endoplasmic reticulum, and Golgi apparatus increased by 100%, 51%, 91%, and 500%, respectively, after hyperoxia. Qualitative analysis showed an altered, ruffled air border with focal areas of cytoplasmic translucency (suggesting injury) and focal areas of subcellular hypertrophy. Exposure to hyperoxia was associated with more organelles being found in peripheral or attenuated portions of type I alveolar cells. Since the increase in type I organelles exceeds the volume of these organelles in its progenitor, the type II cell, it is likely that hyperoxia causes hypertrophy of the type I alveolar epithelium itself, independent of simple type II cell differentiation. Because of the large size and wide distribution of the type I cell, dramatic shifts in cell substructure caused by hyperoxia are more difficult to detect and require quantitative analysis to fully ascertain the extent of cell alterations.