TRITON HYPERLIPEMIA IN DOGS : I. IN VITRO EFFECTS OF THE DETERGENT ON SERUM LIPOPROTEINS AND CHYLOMICRONS

Abstract

Triton WR-1339, a non-ionic detergent, added to canine serum or to ultracentrifugally separated lipoproteins, induced changes in the lipoproteins which were dependent upon concentration of detergent and class of lipoproteins. D 1.063 to 1.21 lipoprotein (α-LP) was especially sensitive to the action of triton. Addition of 2 mg. of triton to 1 mg. of α-LP (based on protein content), induced only slight changes in the electrophoretic and flotation characteristics of the lipoprotein. With a tenfold increase of the detergent (triton:α-LP, 20:1), the mixture, analyzed by starch gel and paper electrophoresis, yielded a tritonlipid complex which remained close to the origin, and a nearly lipid-free protein with electrophoretic mobility higher (starch gel) or lower (paper) than native α-LP. The splitting of the lipid and protein moieties of α-LP could not be clearly shown when the same mixture was analyzed by free boundary electrophoresis. Triton alone moved only slightly in an electrical field (paper, starch gel, Tiselius); it sedimented during ultracentrifugation at D 1.006 and D 1.063 and floated at D 1.21. D 1.006 to 1.063 lipoproteins (β-LP), required larger amounts of triton to show changes. These were evident in 40 to 80:1 mixtures of triton and β-LP. In starch gel and paper electrophoresis triton retained, in a position close to the origin, part of the lipids of β-LP; the remaining β-LP fraction, impoverished of lipids, had electrophoretic mobility similar to native β-LP. The triton-lipid complex sedimented at D 1.063. After addition of triton to complexes [chylomicron-α-P-I ¹³¹] or [lipomul-α-LP-1 ¹³¹], the electrophoretic and ultracentrifugal analyses of these mixtures revealed that the labeled protein was removed from the triglyceride component. Triton also prevented the occurrence of the interaction between lipomul and α-LP and the hydrolysis of both chylomicrons and lipomul-α-LP by lipoprotein lipase. It is postulated that, if the changes in lipoproteins and chylomicrons observed in vitro occur in vivo, they could account, at least in part, for the hyperlipemia which develops in animals following administration of triton.