| Abstract: | Young male rats were fed regular lab chow, or a diet containing 66% of total calories as either glucose or fructose. Both experimental diets led to hypertriglyceridemia, with fasting TG concentrations after one week of 195 +/- 20 and 296 +/- 44 mg/dl for rats fed glucose and fructose, respectively, compared to 94 +/- 10 mg/dl in the control rats. Moderate changes in VLDL composition were observed with both test diets, characterized by slight increases in TG: protein ratio, and increased total cholesterol and phospholipid content. In addition, VLDL isolated from rats fed high carbohydrate diets were increased in size, with a mean VLDL particle diameter of 666 A and 720 A in glucose-fed and fructose-fed rats, as compared to 536 A in control rats. The changes in lipid composition and size of VLDL particles isolated from glucose and fructose-fed donor rats were associated with an increase in their rate of removal from the circulation following their injection into normal recipient rats (half-life time 2.4 +/- 0.2 and 3.2 +/- 0.3 min respectively) as compared to VLDL-TG derived from chow fed donors (4.1 +/- 0.2 min). These data indicate that diets high in either glucose or fructose can lead to both structural and functional changes in VLDL, and provide additional evidence that the ability of fructose to induce profound hypertriglyceridemia is not secondary to a defect in VLDL-TG catabolism. |
