An in vitro model for the catabolism of rat chylomicrons

An in vitro model for the study of the catabolism of chylomicrons is suggested and characterized. The model utilizes the ability of perfused rat hearts to hydrolyze triglycerides of chylomicrons obtained from rat thoracic ducts. The resulting remnants were re-isolated and perfused through rat livers where the remnant lipid and protein was rapidly removed. In contrast intact chylomicrons were taken up by perfused liver to a limited extent. The remnants produced by cardiac perfusion contained a decreased percent of triglycerides and apoproteins C-2 and C-3, with a relative increase primarily in diglycerides and, to a lesser extent, monoglycerides and cholesterol. Most of the ¹²⁵I-labelled remnant protein lost during hepatic perfusion was recovered in the tissue. The model thus simulated many of the known characteristics of chylomicron catabolism in vivo.