The fate of instilled pulmonary surfactant in normal and quartz-treated rats.
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ABSTRACT:
SUBMITTER: Lewis RW
PROVIDER: S-EPMC1147912 | biostudies-other | 1987 May
REPOSITORIES: biostudies-other
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Project description:1. Radioactively labelled pulmonary surfactant was prepared in an isolated perfused lung system provided with [14C]hexadecanoate. 2. After intratracheal administration of pulmonary surfactant radioactively labelled components were rapidly distributed into different lung fractions, including macrophages (free cells), but most of the radioactive label was accumulated by the lung tissue. 3. Alveolar macrophages, maintained in a variety of culture media in the presence and absence of mineral particles, incorporated a low percentage (11%) of radioactively labelled components when incubated with the surfactant, although evolution of labelled CO2 (6% of the original total activity) suggested that some breakdown of the components had taken place. 4. In similar cultures little intracellular accumulation or extracellular release of non-esterified fatty acids was demonstrated, indicating minimal catabolism of the high-molecular-weight lipid components of surfactant (particularly phosphatidylcholine). 5. However, experiments in vitro designed to simulate the lysosomal degradation of endocytosed surfactant indicated that the macrophage had enzymes capable of releasing non-esterified fatty acids, particularly hexadecanoate, from the lipoprotein complex. 6. It is argued that lung cells, other than alveolar macrophages, may also have a role in surfactant turnover.
| S-EPMC1186254 | biostudies-other
Project description:The amount of pulmonary surfactant within type II cells and in the alveolar space, referred to as surfactant pool sizes, are tightly regulated. The molecular pathways that sense and regulate surfactant pool size within the alveolus have not been identified and constitute a fundamental knowledge gap in the field. Our data show that mice with a germline mutation in the orphan G-protein-coupled receptor, GPR116, have a 30-fold accumulation of surfactant phospholipids that causes respiratory distress in adult animals. This phenotype is associated with increased surfactant secretion and induction of the purinergic receptor P2RY2 in young animals, and lipid-laden macrophages and alveolar destruction in older animals. We further demonstrate that GPR116 mRNA expression is developmentally regulated in the murine lung with peak expression at birth when surfactant pool sizes are maximal. Within the lung, GPR116 protein expression is restricted to the apical plasma membrane of alveolar type I and type II epithelial cells. To better understand the roles and molecular mechanisms by which Gpr116 influences gene expression in lung, the effect of cell-selective deletion of Gpr116 (Gpr116D/D) on genome-wide mRNA expression profiles was determined in murine type II alveolar epithelial cells. Differentially expressed genes were identified from Affymetrix Murine GeneChips analysis and subjected to gene ontology classification promoter analysis, pathway mapping and literature mining.
2013-04-10 | E-GEOD-41417 | biostudies-arrayexpress
Project description:The amount of pulmonary surfactant within type II cells and in the alveolar space, referred to as surfactant pool sizes, are tightly regulated. The molecular pathways that sense and regulate surfactant pool size within the alveolus have not been identified and constitute a fundamental knowledge gap in the field. Our data show that mice with a germline mutation in the orphan G-protein-coupled receptor, GPR116, have a 30-fold accumulation of surfactant phospholipids that causes respiratory distress in adult animals. This phenotype is associated with increased surfactant secretion and induction of the purinergic receptor P2RY2 in young animals, and lipid-laden macrophages and alveolar destruction in older animals. We further demonstrate that GPR116 mRNA expression is developmentally regulated in the murine lung with peak expression at birth when surfactant pool sizes are maximal. Within the lung, GPR116 protein expression is restricted to the apical plasma membrane of alveolar type I and type II epithelial cells.
2013-04-10 | GSE41417 | GEO
Project description:The effects of intratracheally instilled silica (10 mg/rat) on the biosynthesis of surfactant phospholipids was investigated in the lungs of rats. The sizes of the intracellular and extracellular pools of surfactant phospholipids were measured 7, 14 and 28 days after silica exposure. The ability of lung slices to incorporate [14C]choline and [3H]palmitate into surfactant phosphatidylcholine (PC) and disaturated phosphatidylcholine (DSPC) was also investigated. Both intra- and extra-cellular pools of surfactant phospholipids were increased by silica treatment. The intracellular pool increased linearly over the 28-day time period, ultimately reaching a size 62-fold greater than controls. The extracellular pool also increased, but showed a pattern different from that of the intracellular pool. The extracellular pool increased non-linearly up to 14 days, and then declined. At its maximum, the extracellular pool was increased 16-fold over the control. The ability of lung slices to incorporate phospholipid precursors into surfactant-associated PC and DSPC was elevated at all time periods. The rate of incorporation of [14C]choline into surfactant PC and DSPC was maximal at 14 days and was nearly 3-fold greater than the rate in controls. The rate of incorporation of [3H]palmitate was also maximal at 14 days, approx. 5-fold above controls for PC and 3-fold for DSPC. At this same time point, the microsomal activity of cholinephosphate cytidylyltransferase was increased 4.5-fold above controls, but cytosolic activity was not significantly affected by silica treatment. These data indicate that biosynthesis of surfactant PC is elevated after treatment of lungs with silica and that this increased biosynthesis probably underlies the expansion of the intra- and extra-cellular pools of surfactant phospholipids.
| S-EPMC1149357 | biostudies-other
Project description:Advances in physiology and biochemistry have provided fundamental insights into the role of pulmonary surfactant in the pathogenesis and treatment of preterm infants with respiratory distress syndrome. Identification of the surfactant proteins, lipid transporters, and transcriptional networks regulating their expression has provided the tools and insights needed to discern the molecular and cellular processes regulating the production and function of pulmonary surfactant prior to and after birth. Mutations in genes regulating surfactant homeostasis have been associated with severe lung disease in neonates and older infants. Biophysical and transgenic mouse models have provided insight into the mechanisms underlying surfactant protein and alveolar homeostasis. These studies have provided the framework for understanding the structure and function of pulmonary surfactant, which has informed understanding of the pathogenesis of diverse pulmonary disorders previously considered idiopathic. This review considers the pulmonary surfactant system and the genetic causes of acute and chronic lung disease caused by disruption of alveolar homeostasis.
| S-EPMC4316199 | biostudies-literature
Project description:BackgroundThe effects of low concentration of sevoflurane on right ventricular (RV) function and intracellular calcium in the setting of pulmonary arterial hypertension (PAH) have not been investigated clearly. We aim to study these effects and associated signaling pathways in rats with PAH.MethodsHemodynamics were assessed with or without sevoflurane inhalation in established PAH rats. We analysis the classic RV function parameters and RV-PA coupling efficiency using steady-state PV loop recordings. The protein levels of SERCA2, PLB and p-PLB expression was analyzed by western blot to assess their relevance in PAH.ResultsRats with PAH presented with RV hypertrophy and increased pulmonary arterial pressure. The values of Ea, R/L ratio, ESP, SW, PRSW, +dP/dtmax and the slope of the dP/dtmax-EDV relationship increased significantly in PAH rats (P<0.05). Sevoflurane induced a concentration-dependent decrease of systemic and pulmonary blood pressure, HR, RV contractility, and increased the R/L ratio in both groups. Sevoflurane reduced the expression of SERCA2 and increased the expression of PLB in both groups. Interestingly, sevoflurane only reduced the p-PLB/PLB ratio in PAH rats, not in normal rats.ConclusionsRats with chronic, stable pulmonary hypertension tolerate low concentrations of sevoflurane inhalation as well as normal rats do. It may be related to the modulation of the SERCA2-PLB signaling pathway.
| S-EPMC4856326 | biostudies-literature
Project description:1. Pulmonary surfactant was isolated from rats that had been exposed to chrysotile asbestos dust for from 3 days to 15 weeks. 2. Asbestos-treated rats showed a progressive increase in amounts of surfactant. After 15 weeks, treated animals contained 4 times as much as non-treated. 3. No significant change was seen in the total protein or total fatty acid composition of surfactant with exposure. 4. The increase in surfactant phosphatidylcholine normally seen on maturation of rat lung was accelerated by exposure of animals to asbestos. 5. An increase in the activity of phosphorylcholine glyceride transferase in lung homogenates and free cell populations was found. 6. Lysosomal phospholipase A was relatively unaffected by dust exposure. 7. It is suggested that the increase in surfactant amounts could be due to an increase in its synthesis without a corresponding alteration in its degradation.
| S-EPMC1165013 | biostudies-other
Project description:Phospholipids in the lung fractions, i.e. alveolar free cells, extracellular pulmonary surfactant, intracellular pulmonary surfactant (lamellar bodies) and microsomal fractions, of rats were examined 28 days after intratracheal injection of silica (40 mg/kg). Significant accumulations of phospholipids were observed in the extracellular- and intracellular-surfactant fractions of rats exposed to silica. The prominent phospholipid accumulated was phosphatidylcholine (PC), consisting mainly of the dipalmitoyl species. However, a compositional change in acidic phospholipids of surfactant fractions was produced by the silica treatment. The percentage of phosphatidylglycerol (PG) was significantly decreased; in contrast, that of phosphatidylinositol (PI) was increased. Thus the ratio PG/PI in the surfactant fractions was markedly decreased in response to silica. This compositional change in both acidic phospholipids occurred even in the early stages, i.e. before appreciable accumulations of alveolar phospholipids were noticed. The molecular-species profiles of both acidic phospholipids in the surfactant fractions were distinctly different from each other. The dipalmitoyl species accounted for more than 30% of PG and less than 6% of PI, respectively. These species patterns of PG and PI were similar in control and silica-treated rats. These findings suggest two possibilities that (1) PG and PI destined for pulmonary surfactant are synthesized from each specific CDP-diacylglycerol (DG) pool having different molecular species in the lung, or (2) individual enzymes responsible for synthesis of surfactant PG and PI have substrate specificities for molecular species of CDP-DG, thereby producing PG and PI having different molecular species in surfactant compartments.
| S-EPMC1133341 | biostudies-other
Project description:Rock dusting is used to prevent secondary explosions in coal mines, but inhalation of rock dusts can be hazardous if the crystalline silica (e.g., quartz) content in the respirable fraction is high. The objective of this study is to assess the quartz content and physical characteristics of four selected rock dusts, consisting of limestone or marble in both treated (such as treatment with stearic acid or stearates) and untreated forms. Four selected rock dusts (an untreated and treated limestone and an untreated and treated marble) were aerosolized in an aerosol chamber. Respirable size-selective sampling was conducted along with particle size-segregated sampling using a Micro-Orifice Uniform Deposit Impactor. Fourier Transform Infrared spectroscopy and scanning electron microscopy with energy-dispersive X-ray (SEM-EDX) analyses were used to determine quartz mass and particle morphology, respectively. Quartz percentage in the respirable dust fraction of untreated and treated forms of the limestone dust was significantly higher than in bulk samples, but since the bulk percentage was low the enrichment factor would not have resulted in any major change to conclusions regarding the contribution of respirable rock dust to the overall airborne quartz concentration. The quartz percentage in the marble dust (untreated and treated) was very low and the respirable fractions showed no enrichment. The spectra from SEM-EDX analysis for all materials were predominantly from calcium carbonate, clay, and gypsum particles. No free quartz particles were observed. The four rock dusts used in this study are representative of those presented for use in rock dusting, but the conclusions may not be applicable to all available materials.
| S-EPMC5009645 | biostudies-literature
Project description:In mammals, oleic acid (OA) induces pulmonary edema (PE), which can initiate acute lung injury (ALI) and lead to acute respiratory distress syndrome (ARDS). Pulmonary surfactant (PS) plays a key role in a broad range of treatments for ARDS. The aim of the present investigation was to assess changes in the synthesis of phosphatidylcholine (PC) from choline and determine the effect of exogenous PS on its de novo synthesis in rats with OA-induced PE. Experimental rats were randomized into three groups, including a control group, OA-induced PE group, and OA-induced group treated with exogenous PS (OA-PS). Twenty-four rats were sacrificed 4 h after induction of the OA model, and tissue was examined by light and electron microscopy to assess the severity of ALI using an established scoring system at the end of the experiment. After 15 ?Ci 3H-choline chloride was injected intravenously, eight rats in each group were sacrificed at 4, 8, and 16 h. The radioactivity of 3H incorporated into total phospholipid (TPL) and desaturated phosphatidylcholine (DSPC) was measured in bronchoalveolar lavage fluid (BALF) and lung tissue (LT) using a liquid scintillation counter and was expressed as counts per minute (CPM). Results showed that TPL, DSPC, and the ratio of DSPC/total protein (TP) in lung tissue decreased 4 h after challenge with OA, but the levels recovered after 8 and 16 h. At 8 h after injection, 3H-TPL and 3H-DSPC radioactivity in the lungs reached its peak. Importantly, 3H-DSPC CPM were significantly lower in the PS treatment group (LT: Control: 62327 ± 9108; OA-PE: 97315 ± 10083; OA-PS: 45127 ± 10034, P < 0.05; BALF: Control: 7771 ± 1768; OA-PE: 8097 ± 1799; OA-PE: 3651 ± 1027, P < 0.05). Furthermore, DSPC secretory rate (SR) in the lungs was significantly lower in the PS treatment group at 4 h after injection (Control: 0.014 ± 0.003; OA-PE: 0.011 ± 0.004; OA-PS: 0.023 ± 0.006, P < 0.05). Therefore, we hypothesize that exogenous PS treatments may adversely affect endogenous de novo synthetic and secretory phospholipid pathways via feedback inhibition. This novel finding reveals the specific involvement of exogenous PS in endogenous synthetic and secretory phospholipid pathways during the treatment of ARDS. This information improves our understanding of how PS treatment is beneficial against ARDS and opens new opportunities for expanding its use.
| S-EPMC5858825 | biostudies-literature