Lung tissue tension and glycosaminoglycans.
This study tested the hypothesis that the loss of tissue tension which occurs when lung parenchyma is immersed in phosphate buffered saline (PBS) follows a loss of glycosaminoglycans (GAG) and/or protein. Tissue tension decay (TTD) was examined in 30 X 30 X 100 micron strips of rat lung parenchyma immersed in PBS in the presence of agents altering the loss of GAG. GAG were labeled with [35S]sulfate in vitro by tissue culture of lung explants and in vivo by intraperitoneal injection of [35S]sulfate. Labeled GAG were lost from lung explants, lung homogenates, and whole lung immersed in saline. The rate of GAG loss was found to correlate with early TTD. In the presence of agents that markedly reduced the leach rate of GAG from lung parenchyma (Safranin O, Alcian Blue, Acridine Orange) there was no TTD. Cetyl-pyridinium chloride was also effective. Polybrene, however, caused a significantly greater TTD than seen in saline with some reduction in the total amount of GAG leached from the tissue. Greater amounts of heparin sulfate were lost in the presence of polybrene. Human serum, dextran-70, ovalbumin, and gelatin significantly reduced but did not prevent TTD. Dextran-70 was effective in reducing the loss of GAG from tissue explants. Agents that reduced disulfide bonds (dithiothreitol, 2-mercaptoethanol) markedly increased TTD and increased the loss of GAG and protein from lung explants and lung homogenates. These studies provide further evidence that lung tissue tension is a function of the interstitial matrix interacting with the connective tissue network. When the GAG and protein responsible for the swelling pressure of matrix are preserved the tissue tension is stable for one hour or more. Agents that partially preserve the matrix are somewhat effective in reducing TTD while those that increase the loss of GAG and protein increase the loss of tension. From the differential effect of agents that retard and accelerate GAG, heparin sulfate (HS) may be the most important GAG to the tissue properties.
D000818:Animals; D002415:Cats; D005260:Female; D006025:Glycosaminoglycans / Q000378:metabolism*; D066298:In Vitro Techniques; D008168:Lung / Q000502:physiology*; D008297:Male; D011506:Proteins / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D006025:Glycosaminoglycans; D011506:Proteins