Alveolar lining fluid

Alveolar lining fluid contains higher concentrations of glutathione (GSH) than found in most extracellular fluids (151). The concentration of GSH in BALF from patients with IPF is 23% of normal (152). Depletion of GSH may place the alveolar space at increased risk of additional injury caused by ROS generated by the influx of inflammatory cells during the inflammatory phase of the development... 

Alveolar lining fluid (98,150-152) and airway mucus (153-155) also contain potent antioxidants, including catalase, superoxide dismutase, peroxidases, and glutathione. These enzymes are physically associated with airway and alveolar surfactant and may serve to protect surfactant from oxidative injury. 

Roveri A, Bruni R, Baritussio A, Coassin M, Benevento M, Baiorino M, Ursini F. Antioxidant defences of rabbit alveolar lining fluid. Respiration 1989 55(suppl 1) 68-73. 

The epithehal cells in the alveoh are covered by a thin layer of so-caUed epithehal hning fluid. This fluid in turn is covered by a monolayer of lung surfactant, which also is present in large amounts in the alveolar hning fluids. Moreover, the lining fluid often contain enzymes that can metabolize drug substances. 

It should be noted that the permeability per surface unit of alveolar epithelium per se is not particularly high. The significant absorption found for various substances after pulmonary administration is rather explained by a number of beneficial factors such as the large surface area of the alveoli, the low volume of the epithelial lining fluid, the relatively thin diffusion layer, the absence of mucociliary clearance from the alveoli as well as the limited enzymatic activity in the lining fluids. 

Jabbour AJ, Holian A, Scheule RK. 1991. Lung lining fluid modification of asbestos bioactivity for the alveolar macrophage. Toxicol App Pharmacol 110 283-294. 

Once a drug aerosol has made its way through the conducting airways to deposit in the deep lung, the major barriers to entering the body are the 0.15 pm layer of type I alveolar cells that are covered by a very thin layer of epithelial lining fluid consisting mainly of surfactant and the relatively permeable endothelium of the alveolar capillaries. Alveolar cells have so called... 

AlAT) has been used in injectable form for the treatment of hereditary AlAT deficiency that markedly increases the risk of development of emphysema. Absorption of aerosolized human plasma and recombinant AlAT into the lymph and blood was studied in sheep and humans. Human plasma AlAT was found in the sheep blood and interstitial lymph at concentrations 1/1000 of that in the alveolar epithelial lining fluid (ELF). The recombinant human AlAT is non-glycosylated and has a terminal methionine residue. In the sheep model, this molecule disappears from the alveolar fluid faster than the human plasma AlAT, with the lymph levels around 10% of ELF and blood levels about 10% of the lymph. The recombinant form... 

Cantin, A.M., North, S.L., Hubbard, R.C. and Crystal, R.G. (1987). Normal alveolar epithelial lining fluid contains high levels of glutathione. J. Appl. Physiol. 163, 152-157. 

Kadota, J., Ishimatsu, Y., Iwashita, T., Matsubara, Y., Kohno, S., Tateno, M., and Ishihara, R. (2(X)0). The ketolide antimicrobial, telithromycin (HMR 3647), achieves high and sustained concentration in alveolar macrophages and bronchoalveolar epitherial lining fluid in healthy Japanese volunteers. Presented at 40th Intersci. Conf. Antimicrob. Agents Chemother. (Sept. 17-20, Toronto). Abstr. No. 2143. 

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