Abstract. Heparin blocks the phorbol ester-induced progression of nontransformed cells through the Go/G, phase

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Three healthy male and three female inpatient volunteers consumed isocaloric diets for 4 wk. At weekly intervals, a fatty meal (100 g fat) was consumed by each fasting subject and blood drawn at 2 h intervals for 12 h. Of the four oral fat loads, two contained saturated fat (polyunsaturated/saturated fat ratio = 0.34) and two contained unsaturated fat (polyunsaturated/saturated fat = 2.21). The magnitude of alimentary lipemia, expressed as area under the plasma triglyceride curve, was 3- to 4-fold higher in males than females. Alimentary lipemia was inversely related to the subjects' fasting plasma high-density lipoprotein (HDL)-cholesterol, HDL apolipoprotein (apo) CIII and directly related to plasma triglycerides. The P/S ratios of the daily diet or the fat meal did not significantly influence the plasma triglyceride curve. After fat intake, mean (+/- SEM) plasma total apoCII and CIII fell to 54 +/- 20% and 73 +/- 5% of base-line, respectively, at 12 h in five of six subjects. After oral fat, an initial fall and a subsequent rise in apoCII and CIII in HDL was associated with reciprocal changes in apoC concentrations in very low-density lipoproteins. We speculate from the data that 1) plasma HDL and their apoC concentrations are important determinants of chylomicron clearance and 2) transfer of apoCs from HDL to triglyceride-rich lipoproteins in the early phase of fat absorption does not result in the total recycling of apoCs from these lipoproteins to HDL during the late phase of alimentary lipemia.

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Organic anions have recently been found to partition in vitro into various biliary lipid particulate species according to their relative hydrophobicities. To establish the physiological relevance of these observations, we intravenously injected various radiolabeled organic anions and assessed the distributions of parent compounds and their metabolites to lipid particles in canine bile. Partitioning into various biliary lipid particles was determined by gel permeation chromatography. Relative hydrophobicities of the various organic anions and their radiolabeled conjugates were determined by reverse-phase high-pressure liquid chromatography. A strong positive correlation (P less than 0.001) was found between percent vesicular association and degree of hydrophobicity for a given organic anion and/or its more polar conjugate. We conclude that 1) the hydrophobic-hydrophilic balance of organic anions is a key factor governing their partitioning to lipid particles secreted in bile; 2) the present study agrees well with our previously published in vitro observations; and 3) other chemical constituents, e.g., proteins, mucin, etc., appear to have little or no effect on organic anion transport in bile.