Inflammatory fluid, plasma, and serum growth factor activity for early passage rabbit fibroblasts. The effect of leukopenia and thrombocytopenia in polyvinyl sponge implanted rabbits

Direct modification of plasma low-density lipoproteins in interstitial inflammatory fluid of the rabbit

Utilizing the polyvinyl sponge-implant model in the rabbit, we have previously demonstrated modification in low-density lipoproteins (LDL) in the extravascular space in association with a cellular inflammatory response. In an attempt to isolate the source of these modifications, plasma LDL was labeled with 125I, and introduced directly into the extravascular space at the time of sponge implantation. [125I] plasma LDL recovered from interstitial inflammatory fluid (IF) at 24 h after implantation demonstrated increased electrophoretic mobility as well as heterogeneity in particle size and hydrated density. These results are in agreement with our previous observations and indicate that modification in IF-LDL probably occurs after it has entered the extravascular space across the vascular wall.

Effect of cholesterol feeding on lipoprotein distribution in interstitial inflammatory fluid of the rabbit

Utilizing the polyvinyl sponge-implant model in the rabbit we have previously demonstrated modification in low density lipoproteins (LDL) of interstitial tissue fluid obtained in association with a cellular inflammatory response. In order to examine the interaction between the inflammatory response and lipoproteins from hypercholesterolemic rabbits, 30 male, New Zealand White rabbits were fed standard chow supplemented with 0.5% cholesterol for 4 weeks prior to sponge implantation. Lipoproteins were prepared from interstitial inflammatory fluid (IF) as well as homologous whole plasma (WP). Total IF cholesterol was positively correlated with plasma cholesterol (459 +/- 43 vs. 1485 +/- 130 mg/dl, means +/- SEM, r = 0.81, P less than 0.01). Distribution of lipoproteins in IF was similar to WP in both particle size and density. Beta-migrating VLDL were the predominant particles in both WP and IF, containing 43.7 +/- 3.4 and 42.2 +/- 5.1% of WP and IF cholesterol, respectively. IF-VLDL were similar to WP-VLDL in lipid and apoprotein composition, morphology and particle size distribution. We conclude from these data that the observed dramatic alterations in lipoprotein distribution in response to a dietary cholesterol challenge in rabbit plasma is essentially unaltered in interstitial inflammatory fluid obtained from these animals.

Normal mitotic reactivity of fibroblasts and mesothelial cells in thrombocytopenic rat

Mitotic reactivity following 48/80-induced mast-cell secretion was studied in the mesentery of rats made thrombocytopenic, 7 days following a single injection of melphalan. In spite of a low platelet count (7% of normal), the mitogenic reaction of the mesenteric fibroblasts and mesothelial cells was normal as judged by DNA-synthesis and mitotic index. The findings suggest that platelets and platelet-growth factors are not essential for the mast-cell-mediated mitogenic reaction of these two types of connective-tissue cells studied in vivo.

Lipoprotein metabolism in the extravascular space. Cyclophosphamide inhibits modification of low-density lipoproteins in interstitial inflammatory fluid of the rabbit

We have recently reported preferential modification and reduction in low-density lipoproteins (LDL) of inflammatory exudates in the rabbit. In an attempt to establish the role of inflammatory cells in these specific alterations, using the sponge-implanted rabbit model we characterized extravascular lipoproteins in animals with severely induced leukopenia. Under these conditions we were unable to demonstrate alterations in the distribution of lipoproteins in inflammatory fluid as compared to homologous plasma. Characterization of LDL from both plasma and inflammatory fluids revealed close similarity in molecular composition and electrophoretic mobility. These studies further implicate the role of scavenger cell systems as a significant component of daily lipoprotein homeostasis.

Circulating phospholipids in interstitial inflammatory fluid of the rabbit

Using a sponge implantation model in the rabbit, we have examined the distribution and fatty acid composition of extravascular phospholipids in interstitial inflammatory fluid. Inflammatory fluid contained less phosphatidylserine and -inositol and a complete absence of phosphatidylethanolamine as compared to autologous plasma. Inflammatory fluid phospholipids contained an increased amount of oleic acid, decreased linoleic acid, and undetectable levels of arachidonic acid, despite unaltered levels of these fatty acids in other extravascular lipid classes as compared to plasma. Potential metabolic consequences of these findings are discussed.