Biomedical subjects

S Matalon

Publications and source records attributed to S Matalon.

At least 91 records · Page 5Linked to original sources

PubMed1993

Oxidant injury to the alveolar epithelium: biochemical and pharmacologic studies.

This multifaceted study involved a combined biochemical and cellular analysis of oxidant metabolism by a lung cell at risk from injury by endogenous and environmental oxidants, the pulmonary alveolar type II epithelial cell. Within the framework of this study, a method was developed for effectively delivering antioxidant enzymes and alpha-tocopherol to the intracellular compartment of alveolar epithelial cells. Alveolar type II cells are key sources of pulmonary surfactant phospholipids and apoproteins and serve as progenitors of type I alveolar epithelium, thus playing an important role in the re-epithelialization of the lung alveolus after exposure to pulmonary oxidants. The type I and II pulmonary epithelium also play an essential collaborative role in maintaining the integrity of the air-blood barrier of the lung. Because of these critical properties of the alveolar epithelium and their recognized sensitivity to oxidant stress derived from diverse sources, such as activated inflammatory cells, hyperoxia, the environmental oxidants and nitrogen dioxide, and surgical procedures, such as cardiopulmonary bypass and lung transplantation, we endeavored to understand more about the oxidant metabolism and antioxidant pharmacology of these cells. In our experiments, we made the observation that loss of differentiated oxidant generation and antioxidant properties of type II cells occurs very rapidly in vitro. For example, we observed a 50% to 75% reduction in the specific activities of type II cell superoxide dismutase, catalase, and glutathione peroxidase, all critical scavengers of cell superoxide and hydrogen peroxide and key enzymes in the attenuation of hydroxyl radical formation. Although the differentiated characteristics of the type II cell antioxidant defenses changed in vitro, they may have become more reflective of type I alveolar epithelial cells. The type I cell is the most vulnerable for oxidant damage in the alveolus because of its large surface area and the possibility of a reduced antioxidant capacity compared to type II alveolar epithelium. In spite of this limitation, we were able to culture type II cells and study their adaptive and toxic responses to exogenously administered oxidant stress. We also observed that a significant source of self-generated oxidants in type II cells was the enzyme xanthine oxidase. Normal rates of oxidant production by this enzyme had an inhibitory effect on incorporation of biosynthetic precursors into surfactant phospholipids; these effects were eliminated by the xanthine oxidase inhibitor, allopurinol.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1992

Biochemical evidence for the presence of an amiloride binding protein in adult alveolar type II pneumocytes.

An amiloride binding protein in adult rat and rabbit alveolar type II (ATII) cells was characterized using three different antibodies against epithelial Na+ channel proteins. We found that 1) polyclonal antibodies raised against epithelial Na+ channel proteins from bovine kidney cross-react with a 135-kDa protein in ATII membrane vesicles on Western blots; 2) using the photoreactive amiloride analog, 2'-methoxy-5'-nitrobenzamil (NMBA), in combination with anti-amiloride antibodies, we found that NMBA specifically labeled the same M(r) protein; and 3) monoclonal anti-idiotypic antibodies directed against anti-amiloride antibodies also recognized this same M(r) protein on Western blots. We also demonstrated a low benzamil affinity binding site (apparent Kd = 370 nM) in rabbit ATII cell membranes and both high and low benzamil affinity binding sites (apparent Kd = 6 nM and 230 nM) in bovine kidney membranes using [3H]Br-benzamil as a ligand. Pharmacological inhibitory profiles for displacing bound [3H]Br-benzamil were also different between ATII cells and bovine kidneys. These observations indicate that adult ATII pneumocytes express a population of epithelial Na+ channels having a low affinity to benzamil and amiloride and a pharmacological inhibitory profile different from that in bovine kidney.

Affinity Labels↗

PubMed1992

Peroxynitrite inhibits sodium uptake in rat colonic membrane vesicles.

Peroxynitrite (ONOO-) is a potent oxidizing agent that initiates lipid peroxidation and sulfhydryl oxidation and may be responsible for a portion of the cytotoxicity attributed to superoxide anion (.O2-). We quantified the extent to which ONOO-, xanthine plus xanthine oxidase (XO) and hydrogen peroxide (H2O2), decreased sodium (Na+) uptake into membrane vesicles derived from colonic cells of dexamethasone-treated rats. Carrier-free 22Na+ uptake into vesicles was measured in the presence of an inside-negative membrane potential, produced by the addition of the potassium ionophore valinomycin (10 microM) after removal of all external potassium by cation exchange chromatography. Preincubation of vesicles with either 100 microM or 1 mM ONOO- for 30 s decreased the amiloride-blockable fraction of Na+ uptake by 27 +/- 7% and 65 +/- 2%, respectively (means +/- S.E.; n greater than or equal to 5; P less than 0.05 from control). However, the amiloride-insensitive part of Na+ uptake was not affected, indicating that there was no overt destruction of these vesicles by these ONOO- concentrations. Decomposed ONOO-, hydrogen peroxide (1 microM-10 mM), or xanthine (500 microM) plus XO (10-30 mU/ml), either in the absence or in the presence of 100 microM FeEDTA, did not decrease Na+ uptake. These data suggest that ONOO- is a potent injurious agent that can compromise Na+ uptake across epithelial cells, possibly by damaging Na+ channels.

Amiloride↗

PubMed1992

Immunocytochemical and functional characterization of Na+ conductance in adult alveolar pneumocytes.

The purpose of this study was to document the existence, assess the spatial localization, and characterize some of the transport properties of proteins antigenically related to epithelial Na+ channels in freshly isolated rabbit and rat alveolar type II (ATII) cells. ATII cells, isolated by elastase digestion of lung tissue and purified by density-gradient centrifugation, were incubated with polyclonal antibodies raised against Na+ channel protein purified from beef kidney papilla (NaAb), followed by a secondary antibody (goat antirabbit immunoglobulin G conjugated to fluorescein isothiocyanate). Rat ATII cells exhibited specific staining with NaAb at the level of the plasma membrane, which, in most cells, colocalized with that of the lectin Maclura pomiferra agglutinin, an apical surface marker. In Western blots, NaAb specifically recognized a 135 +/- 10-kDa protein in rat ATII membrane vesicles. When patch clamped in the whole cell mode using symmetrical solutions (150 mM Na+ glutamate), ATII cells exhibited outwardly rectified Na+ currents that were diminished by amiloride (10-100 microM) instilled into the bath solution. Ion substitution studies showed that the conductive pathways were three times more permeable to Na+ than K+. Amiloride, benzamil, and 5-(N-ethyl-N-isopropyl)-2',4'-amiloride were equally effective in diminishing 22Na+ flux into rabbit and rat ATII cells (45% inhibition at 100 microM, with IC50 of approximately 1 microM for all inhibitors). Tetraethylammonium chloride (10 mM) or BaCl2 (2 mM), well-known K+ channel blockers, had no effect on 22Na+ uptake. These results indicate that ATII cells express an amiloride-sensitive Na+ conductance, probably a channel, with a lower affinity for amiloride and its structural analogues than the well-established amiloride-sensitive Na+ channels found in bovine renal papila and cultured amphibian A6 kidney cells.

Amiloride↗

PubMed1992

Quantitation of alveolar distribution of liposome-entrapped antioxidant enzymes.

Liposome-encapsulated Cu,Zn superoxide dismutase (Cu,Zn SOD) and catalase (CAT) were instilled intratracheally in rabbits, and the temporal and spatial distribution of Cu,Zn SOD and CAT within the lung was assessed at the organ and cellular levels. Specific activities of Cu,Zn SOD and CAT were increased in both lung homogenates and isolated alveolar type II pneumocytes. Peak Cu,Zn SOD activities in lung homogenates and alveolar type II cells were observed 4 h after liposome instillation and returned to control levels by 24 h, whereas CAT activities remained significantly above controls. There were no significant differences in liposome distribution or antioxidant enzyme uptake among lung lobes. The distribution of fluorescently labeled Cu,Zn SOD and CAT was assessed with the use of epifluorescence microscopy and digital image processing to determine patterns of cellular incorporation of liposome-entrapped Cu,Zn SOD and CAT within the lung. Although the mean fluorescence intensity of alveoli from rabbits instilled with liposomes containing labeled Cu,Zn SOD and CAT was greater than autofluorescence observed with either no liposome or empty liposome instillation, fluorescence intensity varied between adjacent alveoli. Both fluorescently labeled Cu,Zn SOD and CAT were located cytosolically, and uptake was not limited to alveolar type II pneumocytes. These results demonstrate that a single intratracheal instillation of liposomes can effect increases in Cu,Zn SOD and CAT activities in distal lung cells, including alveolar type I and type II cells and macrophages.

Animals↗

PubMed1992

Mechanisms of extracellular reactive oxygen species injury to the pulmonary microvasculature.

We investigated the effect of xanthine (X) plus xanthine oxidase (XO) on pulmonary microvascular endothelial permeability in isolated rabbit lungs perfused with Krebs buffer containing bovine serum albumin (5 g/100 ml). Addition of five mU/ml XO and 500 microM X to the perfusate caused a twofold increase in the pulmonary capillary filtration coefficient (Kf,c) 30 min later without increasing the pulmonary capillary pressure. This increase was prevented by allopurinol or catalase but not by superoxide dismutase or dimethyl sulfoxide. Because these data implicated hydrogen peroxide (H2O2) as the injurious agent, we measured its concentration in the perfusate after the addition of X and XO for a 60-min interval. In the absence of lung tissue and albumin, H2O2 increased with time, reaching a concentration of approximately 250 microM by 60 min. If albumin (5 g/100 ml) was added to the perfusate, or in the presence of lung tissue, the corresponding values were 100 microM and less than 10 microM, respectively. To understand the mechanisms of H2O2 scavenging by lung tissue, we added a 250 microM bolus of H2O2 to the lung perfusate. We found that H2O2 was removed rapidly, with a half-life of 0.31 +/- 0.04 (SE) min. This variable was not increased significantly by inhibition of lung catalase activity with sodium azide or inhibition of the lung glutathione redox cycle with 1-chloro-2,4-dinitrobenzene. However, inhibition of both enzymatic systems increased the half-life of H2O2 removal to 0.71 +/- 0.09 (SE) min (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Mechanisms and regulation of ion transport in adult mammalian alveolar type II pneumocytes.

The adult alveolar epithelium consists of type I and type II (ATII) pneumocytes that form a tight barrier, which severely restricts the entry of lipid-insoluble molecules from the interstitial to the alveolar space. Current in vivo and in vitro evidence indicates that the alveolar epithelium is also an absorptive epithelium, capable of transporting Na+ from the alveolar lumen, which is bathed by a small amount of epithelial lining fluid, to the interstitial space. The in situ localization of Na(+)-K(+)-ATPase activity in ATII cells and the fact that these cells are involved in a number of crucial functions, such as surfactant secretion and alveolar remodeling after injury, led investigators to examine their transport characteristics. Radioactive flux studies, in both freshly isolated and cultured cells, and bioelectric measurements in ATII cells grown on porous supports indicate that they transport Na+ according to the Koefoed-Johnsen and Ussing model of epithelial transport. Na+ enters the apical membrane, because of the favorable electrochemical gradient, through Na+ cotransporters, a Na(+)-H+ antiport, and cation channels and is pumped across the basolateral membrane by a ouabain-sensitive Na(+)-K+ pump. Na+ transport is enhanced by substances that increase intracellular adenosine 3',5'-cyclic monophosphate. In addition to Na+ transporters, ATII cells contain several transporters that regulate their intracellular pH, including a H(+)-ATPase, which may explain the low pH of the epithelial lining fluid. The absorptive properties of ATII cells may play an important role in regulating the degree of alveolar fluid in health and disease.

Animals↗

PubMed1991

Mechanisms of H2O2-mediated injury to type II cell surfactant metabolism and protection with PEG-catalase.

Alterations in type II pneumocyte function, including surfactant biosynthesis, may play a significant role in the development and pathophysiology of oxidant-induced lung injury. The results of this study showed that type II cells exposed to 50-300 microM H2O2 demonstrated a dose-dependent decrease in phosphatidylcholine (PC) synthesis with only minimal changes in cell viability. The activities of the choline-phosphate cytidyltransferase and cholinephosphotransferase, specific enzymes of PC synthesis, were not significantly decreased by the exposure. However, the activity of glycerol-3-phosphate acyltransferase, a sulfhydryl-dependent enzyme involved in an early stage of phospholipid synthesis, was decreased by the exposures in a manner that was similar to that seen for PC synthesis. Further studies showed that incubation of type II cells with polyethylene glycol-conjugated catalase for 1 h resulted in an increase in the cell-associated catalase activity (53 +/- 5 vs. 6.7 +/- 1.5 units/mg protein for controls). Confocal microscopy analysis showed that a significant portion of this activity was located intracellularly. More importantly, these cells were protected from changes in PC synthesis rates when subsequently incubated with 300 microM H2O2. These results indicate that the deleterious effects of H2O2 on type II cell surfactant synthesis may be pharmacologically modified in vitro, a concept that may have utility with regard to the modulation of in vivo lung injuries.

Animals↗

PubMed1991

Amiloride-inhibitable Na+ conductive pathways in alveolar type II pneumocytes.

The purpose of these studies was to document the existence of electrogenic Na+ uptake by membrane vesicles of rabbit alveolar type II (ATII) cells and the extent to which this process was inhibited by amiloride. ATII cells (greater than 85% pure) were obtained by elastase digestion of lung tissue followed by Percoll centrifugation, and an enriched plasma membrane vesicle fraction was obtained by differential centrifugation. 22Na+ uptake into these vesicles was measured in the presence of a negative inside membrane potential, produced by the addition of the K+ ionophore valinomycin (10 microM) after all external K+ was removed. Electrogenic (valinomycin-sensitive) Na+ uptake (ELNa) was defined as the difference in uptake in the presence and absence of valinomycin. ELNa, normalized per milligram protein, was twice as high across ATII cells than alveolar macrophage membrane vesicles, was inhibited by amiloride (50% inhibitory concentration = 10 microM), and was decreased in the presence of an outwardly directed proton gradient (pHin 6.8; pHout 7.8), suggesting that it was not mediated by Na(+)-H+ antiport. Furthermore, ELNa was equally inhibited by increasing concentrations of amiloride and benzamil but was more sensitive to 5-(N-ethyl-N-isopropyl)-2'-4'-amiloride in concentrations of 10-1,000 microM. These findings indicate that a fraction of Na+ transport across ATII membrane vesicles occurs through a conductive pathway, probably a channel, that has different sensitivity to amiloride and its analogues than the previously described epithelial high amiloride-affinity Na+ channel.

Alkaline Phosphatase↗

PubMed1990

Characterization of antioxidant activities of pulmonary surfactant mixtures.

Instillation of intratracheal surfactant is known to limit the morbidity and mortality of patients and animals with oxidant-induced lung injury. In this study we quantified the antioxidant properties of natural lung surfactant (NLS), consisting of 90% lipid and 10% protein, and of calf lung surfactant extract (CLSE) consisting of 99% lipid and 1% protein. NLS, but not CLSE, contained significant amounts of superoxide dismutase (SOD) and catalase activities (7 U SOD/mumol phospholipid (PL) and 1 U catalase/mumol PL). More than 90% of the SOD activity was abolished by 1 mM KCN, suggesting that this was the CuZn form of the enzyme. In addition, NLS significantly reduced extracellular H2O2 without losing its ability to reach minimum surface tensions below 1 dyn/cm upon dynamic compression. The NLS scavenging of H2O2 could not be accounted for by albumin. The presence of catalase and SOD activities in NLS was also verified by activity stains of proteins separated by native polyacrylamide gel electrophoresis. Intratracheal instillation of 7 ml of NLS (308 mumol PL) into rabbits significantly increased SOD content in type II cells isolated 12 h later. It is concluded that, in addition to promoting alveolar stability, instillation of pulmonary surfactant may offer significant protection to the alveolar epithelium by scavenging extracellularly generated partially reduced oxygen species and by enhancing intracellular antioxidant enzyme content.

Animals↗

PubMed1990

Endogenous xanthine oxidase-derived O2 metabolites inhibit surfactant metabolism.

The ability of xanthine oxidase (XO)-derived, partially reduced O2 species (PROS) to inhibit surfactant production was examined in freshly isolated alveolar type II (ATII) pneumocytes from New Zealand White rabbits. [Methyl-3H]choline chloride and [1-14C]palmitate incorporation into phosphatidylcholine (PC) decreased in a dose-dependent manner, whereas peak media hydrogen peroxide (H2O2) concentration increased, when 1, 5, or 10 mU/ml XO were added to cell suspensions containing 500 microM xanthine. Addition of 100 microM allopurinol inhibited H2O2 production and abolished the decrease in choline and palmitate incorporation into PC. ATII cells incubated with 500 microM xanthine alone incorporated choline and palmitate at 90 and 80% of control levels, respectively. However, 100 microM allopurinol restored precursor incorporation to control values. To identify a possible intracellular source of PROS, ATII cell xanthine dehydrogenase (XDH) and XO activities were measured. Both total activity (XDH + XO; 45 +/- 7 microU/mg protein) and the percentage activity in the oxidase form (%XO; 30 +/- 4%) remained unchanged in ATII cells incubated in media only (control) for 2 h. In contrast, incubation of ATII cells with 500 microM xanthine resulted in a 50% loss of XDH + XO activity and a 21% increase in %XO within 10 min. After 2 h there was no measurable XDH + XO activity in xanthine-treated cells. Total XDH + XO activity in cells incubated with 500 microM xanthine and 100 microM allopurinol was less than 6% of control values throughout the incubation.(ABSTRACT TRUNCATED AT 250 WORDS)

Allopurinol↗

PubMed1990

Mechanisms of extracellular hydrogen peroxide clearance by alveolar type II pneumocytes.

This study quantified the ability of freshly isolated alveolar type II (ATII) pneumocytes to reduce extracellularly produced hydrogen peroxide (H2O2) and identify the mechanisms involved. ATII cells were isolated to high purity (greater than 85%) from rabbit lungs by enzymatic digestion and Percoll centrifugation and suspended in Eagle's minimum essential medium (MEM). They were then coincubated with either 500 microM xanthine and 10 mU/ml xanthine oxidase (XO; pH 7.4; 25 degrees C) or 300 microM H2O2. The extracellular H2O2 concentration [H2O2] was measured in the following conditions over a 60-min period: 1) MEM alone, 2) untreated (control), 3) 3-amino-1,2,4-triazole (ATZ)-treated, or 4) 1-chloro-2,4-dinitrobenzene-treated ATII cells. Addition of xanthine and XO to MEM alone resulted in a time-dependent increase in [H2O2], reaching a plateau value of approximately 300 microM after 45 min. In the presence of control ATII cells (1 x 10(6) cells/ml), [H2O2] remained at control levels. When coincubated with 300 microM H2O2, ATII cells cleared H2O2 at a higher rate than an equivalent amount of free catalase. Incubation with ATZ decreased ATII cell catalase activity by 89% and significantly impaired their ability to clear H2O2 (half-life = 18.1 +/- 2.7 vs. 1.3 +/- 0.1 min, P less than 0.01). ATZ-treated cells were more susceptible to oxidant injury, as shown by their decreased ability to exclude trypan blue after 60 min of H2O2 exposure. On the other hand, glutathione-depleted cells scavenged H2O2 at the same rate as controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Amitrole↗

PubMed1990

Quantitative ultrastructural study of the rabbit lung: exposure to 60% oxygen for 21 days.

When rabbits were exposed to 60% oxygen for 21 days, arterial PaO2 showed statistically insignificant changes at 6-8 days (69 +/- 5 Torr) and 14-16 days (62 +/- 5 Torr); at 21 days the PaO2 was significantly decreased (56 +/- 5.4 Torr) as compared to 79 +/- 2 Torr at 0 time of exposure. No significant alterations in PaCO2, pH, or hematocrit were present. Morphometric techniques for electron microscopy showed no qualitative or quantitative alterations in lung morphology except for a significant decrease in the volume per lung of the capillary endothelial lumen, possibly reflecting an altered recruitment of capillaries. The total capillary volume per lung however did not differ significantly between oxygen and control-treated rabbits. The physiologic finding of a decreased oxygenation after 60% oxygen exposure suggests that changes in oxygenation precede the morphologic parameters studied.

Animals↗

PubMed1989

Responses of type II pneumocyte antioxidant enzymes to normoxic and hyperoxic culture.

Cultured type II pneumocyte responses to in vitro normoxia (95% air:5% CO2) or hyperoxia (95% O2:5% CO2) were quantified. Normoxic culture (0 to 96 h) of rabbit type II cells resulted in enhanced cell-monolayer protein and DNA content. During this same time, cellular activities of superoxide dismutase (SOD), catalase, and glutathione peroxidase (GSH Px) decreased. Compared to cultures maintained in normoxia, hyperoxic exposure of cultures resulted in decreased cell-associated protein and DNA content. Exposure to hyperoxia also resulted in cytotoxicity as demonstrated by elevated cellular release of DNA, lactate dehydrogenase (LDH), and preincorporated 8-[14 C]adenine. Cellular catalase and GSH Px activities in hyperoxic cells decreased similarly to normoxic controls. In contrast, cellular SOD activity in hyperoxic cells decreased less than in normoxic cultures. Cellular SOD activity in hyperoxic cultures, when normalized for cellular protein, but not DNA, was greater than normoxic values after 24 to 96 h of exposure. Unlike the decrease in cellular antioxidant enzymes during normoxic and hyperoxic culture, cellular LDH activity increased during both these exposures. Cellular LDH activity in 24 to 96 h hyperoxia-exposed cells increased to a lesser extent than normoxic controls. The extent of depression in LDH activity was dependent on whether the activity was normalized for cellular protein or DNA. Type II pneumocytes, which normally undergo hyperplasia and hypertrophy during hyperoxia in vivo, exhibited oxygen sensitivity in vitro. Exposure of type II cells to hyperoxia in vitro resulted in alterations in cellular SOD and LDH activities, but recognition of such changes were dependent on whether enzymatic activities were normalized for cellular DNA or protein.

Adenine↗

PubMed1989

Rigidity of major connectors when subjected to bending and torsion forces.

Rigidity tests were performed on maxillary major connectors of different designs and mandibular major connectors of the lingual bar-type with different cross-sectional shapes and thicknesses. Each major connector was clamped on one side while the other side was subjected to bending, torsion, and bending under torsion forces. Deformation was measured with a micrometer microscope. The most rigid maxillary major connector was the design incorporating the anterior-posterior palatal bar. The most flexible was the U-shaped palatal bar. The full pear-shaped lingual bar (4 x 4 mm) was the most rigid of the major connectors. Among the more conventional lingual bars, the semielliptical bar (3.75 X 1.75 mm) was the most rigid, and the narrow semielliptical bar (4 x 1.5 mm) was the most flexible.

Chromium Alloys↗

PubMed1989

Oxidant inhibition of epithelial active sodium transport.

The purpose of this study was to quantify the effects of extracellularly generated partially reduced oxygen species on active sodium (Na+) transport across the ventral toad skin, a well-studied epithelium. Sections of skin from decapitated toads were mounted in an Ussing chamber, bathed on both sides with electrolyte solution containing 500 microM xanthine and bubbled continuously with room air. The tissues were short-circuited, and short-circuit current (Isc) and tissue resistance (Rt) were monitored continuously with an automatic voltage clamp apparatus. Fifteen mU/ml of xanthine oxidase (XO), either purchased from Calbiochem or purified from cream, were instilled in either the apical (mucosal) or basolateral (serosal) baths at t = 0 and t = 10 min. Hydrogen peroxide (H2O2) concentrations increased to 200 microM within the first 20 min and then decreased, reaching a value of 40 microM by 60 min. Mean [H2O2] was 90 microM. Instillation of XO in the apical bath resulted in a large decrease in Isc and an increase in Rt, their values being 43% and 160% of their corresponding controls 85 min after the first instillation. Addition of superoxide dismutase and catalase completely prevented these changes. Instillation of XO in the basolateral bath had no effect. Similar physiological responses were obtained using the Calbiochem XO or the purified XO, which contained no measurable protease activity. It was concluded that extracellularly generated partially reduced oxygen species may interfere with active Na+ transport by possibly damaging apical Na+ channel proteins.

Animals↗

PubMed1989

Tumor necrosis factor and interleukin 1 alpha increase vascular endothelial permeability.

Endotoxic shock is associated with acute vascular endothelial injury resulting in edema. Tumor necrosis factor (TNF) and interleukin 1 (IL-1) are cytokines produced by endotoxin-stimulated mononuclear phagocytes that are potential mediators of endotoxic shock. In this study, we investigated the effects of TNF and IL-1 alpha on vascular endothelial cell permeability in vitro. The movement of radiolabeled macromolecules of different sizes (57Co-vitamin B12, 125I-cytochrome c, and 131I-albumin; 6.5-35A) across bovine aortic endothelial cell monolayers was measured after exposure to these cytokines. TNF induced a time- and dose-dependent increase in endothelial cell monolayer permeability that was enhanced in the presence of serum. The peak increase was noted after 12 h of incubation with less alteration of permeability with longer incubations. IL-1 alpha caused a similar time-dependent increase in endothelial cell monolayer permeability, but the peak effect of IL-1 alpha was seen after 24 h. Therefore the increased permeability seen with TNF cannot be explained by release of endogenous IL-1 alone. Neither TNF nor IL-1 alpha increased release of [14C]adenine, and the only effect on lactate dehydrogenase release was a small, but statistically significant, increase after 24 h of incubation. From these studies, we conclude that TNF and IL-1 alpha directly increase vascular endothelial cell permeability in vitro and speculate that these cytokines may be involved in the acute vascular endothelial injury associated with endotoxic shock.

Adenine↗

PubMed1989

Alveolar hyperoxic injury in rabbits receiving exogenous surfactant.

We have previously demonstrated that instillation of a calf lung surfactant extract (CLSE) in rabbits after exposure to 100% O2 for 64 h mitigates the progression of lung pathology after return to room air (J. Appl. Physiol. 62: 756-761, 1987). In the present study, we investigated whether we could prevent or reduce the onset and development of hyperoxic lung injury by sequential instillations of CLSE during the hyperoxic exposure. Rabbits were exposed to 100% O2. CLSE (125 mg, approximately 170 mumol of phospholipid) was suspended in 10 ml of sterile saline and instilled intratracheally into their lungs, starting at 24 h in O2, a time at which no physiological or biochemical injury was detected, and at 24-h intervals thereafter. Control rabbits breathed 100% O2 and received either equal volumes of saline or no instillations at all. CLSE-instilled rabbits had higher arterial PO2 (Pao2) values throughout the exposure period and survived longer when compared with saline controls [120 +/- 4 vs. 102 +/- 4 (SE) h; n greater than or equal to 10; P less than 0.05]. At 72 h in O2, CLSE-instilled rabbits had significantly higher lavageable alveolar phospholipid levels (12.5 +/- 1.5 vs. 5 +/- 1 mumol/kg) and total lung capacities (41 +/- 2 vs. 25 +/- 3.5 ml/kg) and lower levels of alveolar protein (24 +/- 3 vs. 52 +/- 8 mg/kg), minimum surface tension (2 +/- 1 vs. 26.1 dyn/cm), and lung wet-to-dry weights (5.9 +/- 0.2 vs. 6.5 +/- 0.3). After 72 h in O2, lungs from both CLSE- and saline-instilled rabbits showed evidence of diffuse hyperoxic injury. However, atelectasis was less prominent in the former. We concluded that instillation of CLSE limits the onset and development of hyperoxic lung injury to the alveolar epithelium of rabbits.

Animals↗