ALIMENTARY LIPEMIA IS ENHANCED IN FIBER-FED RATS

The effect of dietary fiber on the pattern of postprandial lipemia was examined in two studies with male Wistar rats. In the first study, gr oups of rats were killed after food deprivation (0 h) or 1, 4.5 or 8.5 h after a high fat test meal containing either cellulose (CL) or oat bran (OB). Plasma triglycerides (TG) were higher in the OB group at 4. 5 h compared with both the 0-h and the CL-groups at 4.5 h. In both gro ups, LDL and TO-rich lipoprotein cholesterol (TRL-C) concentrations we re higher at 8.5 h than at 0 h; HDL cholesterol was significantly lowe r at 8.5 h than at 0 h for the OB group only. The enhanced lipemia whe n OB was fed may stimulate cholesterol movement from HDL to LDL and TR L. To examine whether TRL secretion rates were responsible for the enh anced lipemia, a second study was conducted. Rats were fitted with jug ular catheters and allowed to recover. Two groups were fed either CL o r OB and infused with Triton-1339 (400 mg/kg). Two control groups were not fed and were infused with either Triton or saline. Rats were kill ed 2.5 h after infusion. Plasma TG was 10-fold higher in the Triton gr oup than in the saline group, but did not differ between the OB and CL groups. The relative contribution of TRL-C to total cholesterol was s ignificantly greater in the Triton control than in the OB and CL group s. Enhanced secretion of TRL was not responsible for the lipemia obser ved in the first study. Rather, alterations in clearance rate were res ponsible.