Extravascular Albumin Research Articles

Serum albumin distribution in early treated anorexia nervosa

We investigated the effects of malnutrition and refeeding on albumin distribution and metabolism in patients undergoing treatment for anorexia nervosa. Using autologous 125I-labelled albumin, we measured the fractional catabolic rate and calculated the relative sizes of the plasma and extravascular albumin pools in 6 female anorexia nervosa subjects and 6 matched controls. We were unable to demonstrate any differences in either the catabolic rate of albumin (fractional or absolute) or in serum albumin concentration between anorexia nervosa and control subjects. There was a large expansion of the extravascular albumin pool in the anorexia nervosa subjects—36% when expressed in relation to body weight. We conclude that, at the time of study, there were no effects of anorexia nervosa on albumin catabolism in these subjects. However, the condition and its treatment are associated with a significant relative expansion of the extravascular albumin pool. This contrasts to some extent with previous work, which suggested that in protein depletion the plasma albumin pool is maintained at the expense of the extravascular albumin pool. The expansion of the extravascular albumin pool is possibly related to the relative excess of interstitial fluid seen in starvation and in the initial phases of refeeding.

HIGH AIRWAY PRESSURE INDUCED LUNG INJURY IS NOT PREVENTED BY PERFLUOROCARBON ASSOCIATED GAS EXCHANGE (PAGE). 2037

Healthy lungs subjected to mechanical ventilation with high airway pressure-high tidal volume develop high permeability edema. We investigated whether the same type of ventilation on perfluorocarbon filled lungs would result in similar damage. Adult rats (350- 500 gm) (BW) were randomized to intermittent positive pressure ventilation with low inspiratory pressure (PIP)- tidal volume (VT) (IPPV) or high pressure - high tidal volume(HIPPV). Within each group, half were randomized to have their lungs initially filled with perfluorocarbon (PF)(APF-140, Air Products and Chemicals. Allentown PA) to functional residual capacity (1ml/100gm BW). Rates were 60 and 25 breaths/ min for the low VT and high VT groups. Arterial blood gases, lung compliance(Cdyn) and pulmonary airway resistance (Raw) were serially measured. After 30 min, the animals were sacrificed and wet and dry lung weights measured to assess extravascular lung water (Qwl) (corrected for lung hemoglobin and fluorocarbon content). Microvascular permeability was assessed by the 30-min 125I-albumin uptake by the lungs and measured as lung (extravascular) albumin space (Alb.Sp). PF normo-ventilation required higher PIP for normocapnea because of significantly higher Raw but did not result in more lung injury. There was no protective effect of PF at high volume ventilation. Table

A role for the beta2 integrin CD11b in mediating experimental lung injury in mice.

We have investigated the requirement of neutrophil emigration and the role for CD11b/CD18-mediated events in the experimental induction of acute lung injury. BALB/c mice received lipopolysaccharide (LPS) (3 mg/kg) intravenously (i.v.) 2 h prior to i.v. zymosan (10 mg/kg) and extravascular albumin accumulation was assessed after 30 min. Compared with saline-treated controls, zymosan alone caused a 6-fold increase in the accumulation of 125I-human serum albumin in whole lung tissue (P<0.05). Combined treatment with LPS and zymosan further increased extravascular albumin accumulation (P<0.05 compared with zymosan alone). The monoclonal antibody 5C6, directed against murine CD11b, was injected, 1 mg i.v. 15 min prior to LPS or 15 min before the zymosan, and compared with immunoglobulin G-injected controls. Albumin accumulation was significantly reduced by 5C6 when given prior to the LPS (P<0.01), but not when given before zymosan in the combined LPS and zymosan treatment. Interestingly, albumin accumulation induced by zymosan alone was not reduced by 5C6. The lungs of the mice treated with LPS and zymosan showed a marked, diffuse accumulation of inflammatory cells which, by light microscopy, appeared to be interstitial. Foci of neutrophil aggregates were seen in noncapillary microvessels, and pretreatment with 5C6 appeared to reduce their frequency. In the animals treated with zymosan alone, LPS alone, or LPS and zymosan in combination, electron microscopy established that approximately 25% of all nucleated cells were neutrophils: 99% of the neutrophils were restricted to the intravascular compartment. Pretreatment with 5C6 prior to LPS and zymosan treatment reduced the increase in percentage of neutrophils by half. These results indicate a disassociation between induction of permeability and neutrophil emigration in our murine model and suggest that the release of neutrophil-derived factors such as platelet-activating factor, proteases, or oxidants may be involved.

Immunohistochemical Localization of Blood-Retinal Barrier Breakdown Sites Associated with Post-Surgical Macular Oedema

Post-surgical macular oedema results from blood-retinal barrier breakdown, but it is not accompanied by structural abnormalities in the retinal vessels or retinal pigmented epithelium. Previous studies, using horseradish peroxidase in a primate model, suggested that leakage occurs primarily through this epithelium. This study was conducted to localize sites of the barrier breakdown in humans following different types of intra-ocular surgery and to compare them with eyes affected with ocular inflammatory disease, ocular infection, and choroidal melanoma. Paraffin sections of eyes were immunohistochemically stained for albumin to localize extravascular albumin, which was graded in a masked study. With aphakia/pseudophakia, penetrating keratoplasty, ocular inflammatory disease, ocular infection, and choroidal melanoma, barrier breakdown occurred primarily at the inner blood-retinal barrier (retinal vasculature), but leakage also occurred at the outer barrier (retinal pigmented epithelium). After retinal re-attachment surgery, the inner and outer blood-retinal barriers were equally compromised. Vascular leakage in the optic nerve head coincided with barrier failure in these disorders. The widespread pattern of blood-retinal barrier compromise with leakage at multiple sites suggests that soluble mediators are likely to play a role in postsurgical macular oedema, ocular inflammatory disease, and choroidal melanoma.

The effects of experimental malnutrition on albumin metabolism and distribution in rabbits.

In order to determine the extent to which the concentration of albumin in plasma is maintained at the expense of the extravascular pool during protein-energy malnutrition, the rates of exchange between albumin in plasma (IA) and the extravascular pool (EA) and consequently the distribution of albumin between intravascular and extravascular pools (expressed as EA:IA) were measured in protein-energy-depleted and control rabbits. The fractional rates of synthesis (FSR) and catabolism (FCR), the concentration of albumin and the plasma volume (PV) were also measured. In animals in which protein-energy intake was reduced by 58% the concentration of albumin in plasma remained unchanged, whereas FCR decreased by 38% and FSR by 30%. No significant changes in EA:IA or PV were found. We conclude that albumin concentration during protein-energy depletion is not maintained at the expense of extravascular albumin, but by parallel changes in the rates of catabolism and synthesis.

Immunohistochemical localization of blood-retinal barrier breakdown sites associated with post-surgical macular oedema

Post-surgical macular oedema results from blood-retinal barrier breakdown, but it is not accompanied by structural abnormalities in the retinal vessels or retinal pigmented epithelium. Previous studies, using horseradish peroxidase in a primate model, suggested that leakage occurs primarily through this epithelium. This study was conducted to localize sites of the barrier breakdown in humans following different types of intra-ocular surgery and to compare them with eyes affected with ocular inflammatory disease, ocular infection, and choroidal melanoma. Paraffin sections of eyes were immunohistochemically stained for albumin to localize extravascular albumin, which was graded in a masked study. With aphakia/pseudophakia, penetrating keratoplasty, ocular inflammatory disease, ocular infection, and choroidal melanoma, barrier breakdown occurred primarily at the inner blood-retinal barrier (retinal vasculature), but leakage also occurred at the outer barrier (retinal pigmented epithelium). After retinal re-attachment surgery, the inner and outer blood-retinal barriers were equally compromised. Vascular leakage in the optic nerve head coincided with barrier failure in these disorders. The widespread pattern of blood-retinal barrier compromise with leakage at multiple sites suggests that soluble mediators are likely to play a role in postsurgical macular oedema, ocular inflammatory disease, and choroidal melanoma.

Electron Microscopic Immunocytochemical Evidence for the Mechanism of Blood-Retinal Barrier Breakdown in Galactosemic Rats and its Association with Aldose Reductase Expression and Inhibition

Blood-retinal barrier (BRB) breakdown occurs in human diabetic retinopathy and can lead to significant loss of vision. The galactosemic rat serves as a model for human diabetic retinopathy and develops many of the same ocular complications, including BRB failure. Aldose reductase (AR), an enzyme in the polyol pathway, has been implicated in several of these complications. Electron microscopic immunocytochemical staining for albumin can be used to visualize extravasated albumin in control and galactosemic rats with and without AR inhibition to reveal the mechanism for galactosemia-related BRB failure without the use of tracer substances, and to determine whether AR activity influences this mechanism. Electron microscopic immunocytochemical labeling of AR can reveal the cellular distribution of AR in normal and galactosemic rat retina and determine whether a correlation exists between BRB breakdown and AR expression in cells that form or influence the BRB. Extravascular albumin is demonstrable as early as 2·5 months in galactosemic rats, which is prior to the presentation of ultrastructural changes. Albumin-positivity is visualized in retinal vascular endothelial (RVE) cell cytoplasm from galactosemic rats both diffusely and within vesicles, but it is not detected in comparably aged normal rat RVE cells or within the tight junctions of the RVE or RPE (the cells that form the BRB) in control or galactosemic rats, suggesting that BRB breakdown in galactosemic rats may be mediated through two mechanisms: a permeation of the RVE cell membrane leading to diffuse cytoplasmic positivity for albumin, and vesicular transport across the RVE. The AR inhibitor, sorbinil, prevents diffuse cytoplasmic staining of RVE cells, but not vesicular staining, implying that RVE membrane permeability may be altered by AR activity, but vesicle formation does not appear to be affected. AR was immunocytochemically demonstrated in some RVE cells from galactosemic rats, but not from controls. In perivascular astrocytes, which may influence the integrity of the inner BRB, AR labeling was augmented in galactosemic rats. Increased AR expression in RVE cells and perivascular astrocytes from galactosemic rats provides additional support for a role for AR in galactosemia-related BRB failure.

Physiology: Morphological characteristics of preimplantation stage endometrium in the rhesus monkey

The morphological characteristics of endometrium on day 6 after ovulation of conception (group 1) and non-fecund, menstrual (group 2) cycles have been studied in the rhesus monkey (n = 30). A conception cycle was distinguished by the presence of a developmentally normal, age-stage-synchronized embryo. Thus, 78% of the mated cycles (n = 18) yielding synchronous embryos (12 zona-encased and two zona-free blastocysts) were used for this study. On day 6 after ovulation, no significant changes in the serum concentrations of oestrogen and progesterone were seen in conception cycles (n = 14) compared with the non-mated, normal ovulatory cycles (n = 12). Morphometric analyses revealed that on day 6 of gestation (n = 8), endometrium differed from the corresponding non-mated luteal phase (n = 7) with significant increases in epithelial mitosis (P < 0.01), height of glandular epithelium (P < 0.05), volume ratio of gland cell to gland (P < 0.03), degree of pseudostratification (P < 0.02), and higher frequency of supranuclear, adluminal accumulation of vacuoles in gland cells (P < 0.05). The degree of stromal oedema was higher (P < 0.02) in fecund cycles but there was no change in venular diameter. In a separate set of experiments, estimates of tissue vascular response revealed a higher (P < 0.02) endometrial extravascular albumin space on the same day of gestation; there were no differences, however, in endometrial blood volume, or in the number of von Willebrand antigen-positive capillaries and small vessels between the two groups (group 1, n = 6; group 2, n = 5).(ABSTRACT TRUNCATED AT 250 WORDS)

Increased pulmonary vascular permeability in rats with biliary cirrhosis: role of thromboxane A2.

Rats with liver cirrhosis exhibit arterial hypoxemia and loss of hypoxic pulmonary vasoconstriction similar to some patients with end-stage liver disease. We hypothesized that the pulmonary circulatory dysfunction in cirrhosis results from vascular endothelial cell injury and interstitial lung edema. To investigate this hypothesis, we compared the extravascular lung albumin leak, lung ultrastructural changes, and tissue eicosanoid levels in control and cirrhotic rats. In comparison to sham-operated controls, rats with biliary cirrhosis, 6 wk after ligation of the common bile duct, had increased lung albumin leak index (1.46 +/- 0.12 vs. 0.80 +/- 0.04, P < 0.001) and bloodless lung wet-to-dry weight ratio (4.94 +/- 0.05 vs. 4.78 +/- 0.03, P < 0.05). Electron-microscopic sections of lungs from cirrhotic rats demonstrated infiltration with intravascular macrophage-like cells, endothelial cell injury, and interstitial edema. In addition, lung tissue thromboxane B2 was significantly increased in cirrhotic rats, and pretreatment with a thromboxane synthase inhibitor, dazoxiben, reduced lung thromboxane B2 level and attenuated extravascular lung albumin leak (control 1.03 +/- 0.07, cirrhotic 2.29 +/- 0.06, cirrhotic plus dazoxiben, 1.57 +/- 0.17). In contrast, WEB 2086, a platelet-activating factor antagonist, had no effect on lung albumin leak. We conclude that pulmonary vascular permeability is increased in rats with biliary cirrhosis and that thromboxane A2 contributes to the pulmonary circulatory abnormalities in cirrhosis.

Structure-function relationship in secondary biliary cirrhosis in the rat: Stereologic and hemodynamic characterization of a model

Secondary biliary cirrhosis in the rat is an attractive model since unlike other models it does not rely on exogenous toxic compounds to induce cirrhosis. However, because little is known about the microcirculatory abnormalities of this model, this study investigated hemodynamics in rats with predefined functional impairment and related them to different aspects of stereologically quantified structure. All animals with at least 50% reduction in microsomal function, assessed by the aminopyrine breath test, had portal hypertension. The sinusoidal space, as assessed by multiple indicator dilution in the perfused liver, was reduced whereas large vessel space was increased. This reduction in sinusoidal space could contribute to increased portal resistance. The degree of intrahepatic shunting varied as assessed by a microsphere technique (13.9 vs. 0.5% in controls). These alterations were confirmed by stereological analysis. Numerically, there was excellent agreement between functional indicator dilution data and anatomic quantitation. Microvascular exchange was impaired as in other models of cirrhosis as shown by a reduced extravascular albumin space (4.5 vs. 2.2%, p < 0.01). In contrast to alterations in vascular space, this functional impairment was not reflected in the stereologically assessed space of Disse which averaged 5% of liver volume in both groups. Finally, in spite of reduced microsomal function in vivo (aminopyrine breath test) and in vitro (aminopyrine N-demethylase activity), the smooth endoplasmic reticulum was maintained (4.3 vs. 3.5 m2/ml cytosol, n.s.), which demonstrates that microsomal function in this model is reduced per unit hepatocyte. This suggests that the sick-cell hypothesis applies to secondary biliary cirrhosis in the rat.

Exudation of fibronectin and albumin after spinal cord injury in rats

Spinal cord of the rat was investigated immunohistochemically to detect signs of extravasation of fibronectin in animals in which the cord was subjected to different degrees of compression trauma. Immunohistochemistry was performed after survival periods of 4 and 24 h and parallel sections were incubated for albumin immunoreactivity to detect signs of breakdown of the blood-spinal cord barrier. Extravascular reaction products indicating the presence of fibronectin were found within and in the vicinity of the compression provided that bleeding had occurred in the spinal cord, i.e., in rats with severe trauma. Immunoreactive material indicating extravascular albumin was present in the traumatized region and in many segments of the cord located away from the compressed part. Such material was seen both proximal and distal to the primary injury and even in rats with a low magnitude of compression. Generally, with more severe trauma and longer survival periods extravascular albumin was more extensively distributed along the cord. No signs of fibronectin antigen were detected in spinal cord segments away from the compression even though such regions showed albumin immunoreactivity outside the vessels. The results indicate that within and close to the primary injury of compressed spinal cord exudation of fibronectin may occur from the plasma of microvessels provided that the impact is severe enough to cause intramedullary hemorrhages.

Growth factor activity in the lung during compensatory growth after pneumonectomy: evidence of a role for IGF-1

Unilateral pneumonectomy in rats causes compensatory growth of the remaining lung. During this growth, there are large increases in the cell numbers and in the rates of collagen and non-collagen protein production. We examined possible mechanisms by which these changes might occur. Assessment of the effect of bronchoalveolar lavage (BAL) fluid on fibroblasts in vitro demonstrated the presence of stimulatory activity for fibroblast replication in control animals. This activity was greatly increased two and six days postpneumonectomy (115 +/- 26% and 75 +/- 18% above control values, respectively), but had returned to normal by 14 days. Preliminary characterization suggests that the activity is heat labile and consists of at least two moieties with apparent molecular weights of 5-15 kD and 70-220 kD. The activity was partially blocked by antibodies to insulin-like growth factor-1 (IGF-1), and levels of IGF-1 were increased by about 100% (p less than 0.001) two days after pneumonectomy compared with control values. Examination of BAL cells demonstrated an early influx of leucocytes into the remaining lung of pneumonectomized rats. At two days, about 25% of the lavageable cells were neutrophils, but macrophages were the predominant cell type at all times. The extravascular albumin space of the lung increased by about 65% (p less than 0.01), six days after pneumonectomy. The influx of circulatory proteins and cells are potential sources of the increased mitogenic activity observed in the lung.

Albumin escape from microvessels in kidney, heart and skeletal muscle in experimental diabetes mellitus in the anaesthetized rat

Diabetes was induced with streptozotocin in rats weighing about 160 g. These were maintained with age-matched controls for up to 14 months, blood glucose being periodically monitored. Half the diabetic and control rats received the aldose reductase inhibitor, Ponalrestat, in their diet. Distribution of volumes of 131I-albumin (5 min) and 125I-albumin (100 min) were estimated in various tissues at 3 weeks, 6-7 months and 13-14 months of diabetes. The former space was assumed to represent the intravascular plasma space, while the latter was taken to include both the extravascular and intravascular albumin volumes in the kidney. In heart and skeletal muscle, equilibration between the specific activities of extravascular albumin and of plasma albumin was not assumed to be complete at 100 min. In the cortex and medulla of kidney, the extravascular albumin pool increased significantly at 13-14 months of diabetes (for both, P less than 0.01). Significantly increased entry of albumin into the interstitium occurred at 6 months (P less than 0.05) and at 13-14 months (P less than 0.01) in skeletal muscle, and at 13-14 months (P less than 0.05) in heart. The intravascular plasma volumes were not influenced by diabetes and the aldose reductase inhibitor had no effect at any time in either diabetic or control rats. These findings indicate increased movement of plasma albumin into the interstitium in the late phase of diabetes in the heart, skeletal muscle and in the kidney. Enlargement of the interstitial albumin pool is likely to affect the fluid balance between capillary and interstitium and may contribute to the effect of diabetes on the function of these organs.

Permeability of blood‐brain and blood‐nerve barriers in experimental diabetes mellitus in the anaesthetized rat

Diabetes was induced with streptozotocin in rats weighing about 160 g. These were maintained with age-matched controls for up to 14 months, blood glucose being periodically monitored. Half the diabetic and control rats received the aldose reductase inhibitor, Ponalrestat, in their diet. At 3 weeks, 6-7 months and 13-14 months, the vascular permeability in regions of brain, and in optic and sciatic nerves, were measured by maintaining radiotracers in the bloodstream--125I-albumin (100 min), [14C]sucrose (60 min) and 131I-albumin (5 min)--followed by tissue sampling and counting at termination. 131I-albumin estimated residual intravascular plasma. Diabetes of up to 13-14 weeks caused no measurable increase in the sucrose permeability of microvessels in eight different brain regions, in optic or in sciatic nerve. At 3 weeks of diabetes, sucrose permeability in all brain regions and in optic nerve was reduced relative to that in controls. Extravascular albumin entry into different regions of brain and optic nerve was insignificant and insensitive to diabetes, except in the hypothalamus and optic nerves where it was raised with increasing duration of diabetes. In sciatic nerve, extravascular albumin distribution was markedly increased by diabetes, but sucrose permeability was not demonstrably affected. At the level used in the diet, Ponalrestat reduced the sorbitol content of diabetic sciatic nerve but did not protect again the increased permeability to albumin.

An atypical vasopermeability response to leukotrienes in the iris-ciliary body

The effects of leukotrienes (LTs) on the blood-aqueous barrier in the guinea pig were investigated. Leukotriene B 4 (LTB 4) and D 4 (LTD 4) were administered in doses of 1 to 1000 ng into the anterior chamber. Plasma extravasation was determined as extravascular 125I-albumin levels in the iris-ciliary body using 125I-albumin and 51Cr-erythrocytes as an intravascular marker. LTB 4 and LTD 4 alone did not cause significant plasma extravasation. Although combinations of 100 ng and more of each LT raised extravascular albumin levels in the ocular anterior uvea. These studies suggest a synergistic interaction of LTB 4 and LTD 4 with respect to plasma extravasation in the iris-ciliary body. These results further support a possible involvement of LTs in uveal inflammatory diseases.

Tissue to plasma capillary permeability of 131I-albumin in the perfused rabbit ear

The tissue to plasma transfer of 131I-albumin was recorded in perfused rabbit ears ( n = 6) following equilibration for 24 hr. 125I-fibrinogen served as the plasma marker, and was introduced intravenously 15 min before clamping. The ears were rollerpump perfused with isotonic diluted plasma at a constant rate of (mean ± SD) 5.1 ± 1.5 ml (min · 100 g) −1. The mean extravascular albumin distribution volume was 12.4 ± 1.1 ml · 100 g −1, and the fibrinogen volume (plasma volume in tissue) was 3.1 ± 0.4 ml · 100 g −1 as determined from biopsies of the contralateral ear. The initial transfer of albumin was marked, and occurred at rates corresponding to a unidirectional clearance (Cl(0)) of 0.068 ± 0.012 ml (min · 100 g) −1. However, with a reduction of mean interstitial albumin tracer content of no more than 4%, net transport decreased to reach slowly declining levels 5 to 10 times lower within 10 min of continued perfusion. The decrease was considered due to rapid exhaustion of a small interstitial pool of tracer immediately adjacent to the exchange vessel membrane, followed by an increasingly retarded outwash from more distant areas. The results suggest a bimodal structural resistance to albumin movement: a relatively low resistance in the capillary membrane, and a considerable restriction to albumin transport located within the interstitial space.

Pulmonary blood volume and edema in postpneumonectomy lung growth in rats

After pneumonectomy in young animals, the contralateral lung undergoes compensatory growth and generally attains the same weight and air space volume as both lungs in age-matched controls. In this study, we determined the contribution of lung edema and increased blood volume to the weight gain in rats. Three weeks after pneumonectomy (n = 18) or sham pneumonectomy (n = 17), the pulmonary blood volume and the extravascular water and albumin were evaluated by use of 51Cr-labeled erythrocytes and 125I-labeled albumin. The air space volume, blood-free lung weights, and DNA and protein content were also compared. The data show that the total pulmonary blood volumes and the blood volume per gram of blood-free dry lung were similar in pneumonectomized and age-matched sham controls. The total extravascular albumin and the extravascular albumin per gram of blood-free dry lung were also similar as well as the extravascular lung water, wet-to-dry weight ratios, DNA and protein content, and air space volumes. These data indicate that the increased weight of the postpneumonectomy lung was due to cellular and stromal proliferation. The blood volume and interstitial fluid increased in proportion to the increase in lung parenchyma. Neither vascular congestion nor increased extravascular protein and water contributed to the observed weight gain.

Bleomycin-induced lung injury in the rat: effects of the platelet-activating factor (PAF) receptor antagonist BN 52021 and platelet depletion.

Bleomycin is a highly effective antitumor agent, but pulmonary toxicity, characterized by an acute inflammatory reaction and associated pulmonary edema, limits clinical use of the drug. Platelets and platelet-activating factor (PAF), a membrane-derived phospholipid, have been implicated in the mechanisms that can mediate pulmonary microvascular injury. We sought to investigate the role of PAF in bleomycin-induced lung injury in the rat, using the PAF receptor antagonist BN 52021; and the role of platelets though the use of an anti-platelet antibody. Lung injury was induced by intratracheal bleomycin (1.5 mg) and assessed by measurements of lung wet weight and total pulmonary extravascular albumin space (TPEAS). Bleomycin caused a significant increase in both indices after 48 hr, compared with control animals (p less than 0.05). A single dose of BN 52021 (20 mg/kg orally) significantly reduced the bleomycin-induced increase in lung weight, but not the rise in TPEAS (p greater than 0.05). Increasing the dose of BN 52021 (20 mg/kg/12 hr, orally) had no additional effect. Reducing circulating platelet numbers by approximately 75% had no effect on either the increase in lung weight or TPEAS, observed 48 hr after bleomycin (p greater than 0.05). PAF may partially contribute to the acute inflammatory reaction seen after intratracheal bleomycin in rats.

Evaluation of Reexpansion Pulmonary Edema Following Unilateral Pneumothorax in Rabbits and the Effect of Superoxide Dismutase

We investigated the lung injury that occurs following reexpansion of a unilateral pneumothorax and determined the effect of superoxide dismutase (SOD) infused immediately prior to reexpansion on this injury. After 7 days of at least 80% right pneumothorax, rabbits received intravenous infusions of either SOD (n = 7), heat-inactivated SOD (n = 1), or vehicle (n = 7) immediately before lung reexpansion. Lung injury was assessed by measuring the systemic white cell counts, pulmonary blood volumes, extravascular albumin, extravascular lung water, wet/dry weight ratios, and histology 2 h after reexpansion. The reexpanded lung showed increased extravascular albumin, extravascular lung water and wet/dry weight ratios with decreased blood volumes compared to the uninjured lung. SOD delayed the onset of leukopenia and neutropenia at 3 and 7 min after reexpansion, but the white cell counts had decreased to the same level in both groups by 30 min. SOD had no effect on the degree of injury after 2 h. While a single bolus of SOD given immediately before reexpansion delayed the onset of this injury, it did not affect the injury that subsequently developed in the lung.

A new method to evaluate extravascular albumin and blood cell accumulation in the lung.

A method was developed to evaluate blood volume, accumulation of extravascular albumin (ALBev), and platelet (PL) or polymorphonuclear neutrophil (PMN) sequestration in lungs after challenge with inflammatory agents. Erythrocytes (RBC), albumin, and PL or PMN, labeled with 99mTc, 131I, and 111In,-respectively, were injected intravenously into anesthetized and ventilated guinea pigs. The different parameters were calculated from in vivo lung and blood radioactivity values. When N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP) was injected intravenously at 10 micrograms.kg-1, lung RBC content dropped by 14.7 +/- 1.8% (SE; n = 10), indicating a reduced lung blood volume, ALBev rose to 15.0 +/- 3.2% of the initial albumin vascular content, and the circulating PMN were sequestered by 9.2 +/- 1.7%. A transient PL sequestration was also observed 1 min after the injection of fMLP (13.1 +/- 2.0%, n = 7). During the infusion of 1-O-hexadecyl-2-acetyl-sn-glycero-3-phosphorylcholine, the lung PL content rose dose dependently from 10.1 +/- 2.2% of the circulating pool with 3 ng.kg-1.min-1 to 54.9 +/- 20.1% with 44 ng.kg-1.min-1, the lung RBC content decreased by greater than 10%, and the ALBev increased beyond 16%. Our method allows the study of the correlations between cell entrapment and the variations of the albumin exchanges in the lung and may lead to a better understanding of the correlations between cell activation and edema.