出版社：American Society for Biochemistry and Molecular Biology
摘要：Triglyceride (TG) enrichment of high density lipoproteins (HDL) in hypertriglyceridemic states renders the particles vulnerable to lipolysis, which reduces their size. In the present study we modified the size and composition of HDL in vivo in hypertriglyceridemic humans by administering a bolus of intravenous heparin, and tested the subsequent clearance of the isolated HDL particles in rabbits and rats. HDL was isolated by ultracentrifugation from 21 moderately hypertriglyceridemic humans, 5 h after ingestion of a high fat meal and then 15 min after an intravenous heparin bolus (60 U/kg). Postprandial large TG-rich preheparin HDL and small, TG-poor postheparin HDL were labeled with either 125I or 131I. The clearance of apoA-I associated with each HDL tracer was determined by injecting the tracers 1) simultaneously (n = 13) and 2) sequentially (n = 8) into male New Zealand White rabbits, an hepatic lipase-deficient animal, and 3) by injecting the tracers simultaneously into male Sprague-Dawley rats (n = 8), an animal that has hepatic lipase. Die-away curves of each radiolabeled tracer were analyzed using a two-pool model that assumes the existence of an intravascular pool in dynamic equilibrium with an extravascular pool. In the rabbit studies, the fractional catabolic rate (FCR) of small, postheparin TG-poor HDL was greater than the FCR of the larger TG-rich HDL (11% greater in the simultaneous study, P
