Lipid absorption in unanesthetized, unrestrained rats. Effects of 4-aminopyrazolopyrimidine and ethinyl estradiol

Emulsified triacylglycerol containing [14C]palmitate was infused intraduodenally in unanesthetized, unrestrained animals treated with 4-aminopyrazolopyrimidine or pharmacologic doses of ethinyl estradiol. 4-Aminopyrazolo-pyrimidine practically eliminated the appearance of radioactivity in plasma but in ethinyl estradiol-treated animals the peak of radioactivity and shape of the plasma curve were similar to control, although lower in amplitude. A delayed appearance of radioactivity was also observed in 48-h- compared to 15-h-fasted controls, suggesting a requirement for induction of lipoprotein production prior to fat absorption.