Turnover of low-density lipoprotein isolated from interstitial inflammatory fluid of the rabbit.

Utilizing the polyvinyl sponge-implant model in the rabbit, we have described in vivo modification of low-density lipoproteins (LDL) in interstitial inflammatory fluid (IF). In the present studies, plasma clearance rates of IF-LDL were determined and compared with normal whole plasma LDL (WP-LDL) as well as plasma LDL modified by chemical reaction with acetic anhydride (Ac-LDL). Lipoproteins were labeled with 125I and injected into the lateral ear vein of recipient rabbits. At 10 min after injection, only 51.5% of IF-LDL could be accounted for in recipient plasma, as compared to 91.9% for WP-LDL, and 2.4% of Ac-LDL. Subsequent log-linear decay rates were similar for IF-LDL and WP-LDL (t 1/2 = 9.5 vs. 11.0 h). Autoradiography of plasma obtained from recipient animals at 15 min and 1 h after injection revealed a return to normal electrophoretic mobility of [125I]IF-LDL. These results indicate that IF-LDL is a mixture of both modified and essentially unmodified particles. We propose that the modified particles may be removed from the circulation by mechanisms described for Ac-LDL.