The effect of partial ileal bypass on receptor-mediated uptake and catabolism of low density lipoprotein in the rhesus monkey.

The fractional rates of catabolism (FCR) of 125I-labelled low-density lipoprotein (LDL) and 131I-labelled LDL coupled with 1,2-cyclohexanedione (LDL-CHD) were determined before and 6 weeks after partial ileal bypass in three Rhesus monkeys. Receptor-mediated catabolism, determined as the difference between the FCRs of 125I-LDL and 131I-LDL-CHD, increased significantly after partial ileal bypass. Analysis of tissue distribution of radioactivity in one monkey, killed at the conclusion of a third turnover study 6 months after partial ileal bypass, suggested that the liver was the main tissue site of accumulation of LDL, and that uptake had occurred mainly via a receptor-mediated mechanism. It is concluded that partial ileal bypass stimulates receptor-mediated LDL catabolism in the Rhesus monkey as in man, and that this increase is probably mediated via hepatic LDL receptors.