Compositional changes in lipid microdomains of air-blood barrier plasma membranes in pulmonary interstitial edema.
We evaluated in anesthetized rabbits the compositional changes of plasmalemmal lipid microdomains from lung tissue samples after inducing pulmonary interstitial edema (0.5 ml/kg for 3 h, leading to approximately 5% increase in extravascular water). Lipid microdomains (lipid rafts and caveolae) were present in the detergent-resistant fraction (DRF) obtained after discontinuous sucrose density gradient. DRF was enriched in caveolin-1, flotillin, aquaporin-1, GM1, cholesterol, sphingomyelin, and phosphatidylserine, and their contents significantly increased in interstitial edema. The higher DRF content in caveolin, flotillin, and aquaporin-1 and of the ganglioside GM1 suggests an increase both in caveolar domains and in lipid rafts, respectively. Compositional changes could be ascribed to endothelial and epithelial cells that provide most of plasma membrane surface area in the air-blood barrier. Alterations in lipid components in the plasma membrane may reflect rearrangement of floating lipid platforms within the membrane and/or lipid translocation from intracellular stores. Lipid traffic could be stimulated by the marked increase in hydraulic interstitial pressure after initial water accumulation, from approximately -10 to 5 cmH2O, due to the low compliance of the pulmonary tissue, in particular in the basement membranes and in the interfibrillar substance. Compositional changes in lipid microdomains represent a sign of cellular activation and suggest the potential role of mechanotransduction in response to developing interstitial edema.
Palestini
Paola
P
Dipartimento di Medicina Sperimentale, Ambientale e Biotecnologie Mediche, Università di Milano-Bicocca, Via Cadore 48, 20052 Monza, MI Italy.
Calvi
Chiara
C
Conforti
Elena
E
Daffara
Rossella
R
Botto
Laura
L
Miserocchi
Giuseppe
G
D000818:Animals; D051398:Aquaporin 1; D051402:Aquaporin 5; D020346:Aquaporins / Q000378:metabolism; D015824:Blood-Air Barrier / Q000378:metabolism*; D051242:Caveolin 1; D022461:Caveolins / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D003902:Detergents / Q000494:pharmacology; D004351:Drug Resistance; D005455:Fluorescent Antibody Technique; D005677:G(M1) Ganglioside / Q000378:metabolism; D050356:Lipid Metabolism; D008168:Lung / Q000187:drug effects / Q000378:metabolism; D021962:Membrane Microdomains / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D011654:Pulmonary Edema / Q000378:metabolism*; D011817:Rabbits
D051402:Aquaporin 5; D020346:Aquaporins; D051242:Caveolin 1; D022461:Caveolins; D003902:Detergents; D008565:Membrane Proteins; C106354:flotillins; D051398:Aquaporin 1; D005677:G(M1) Ganglioside