The absorption and subsequent utilization of lecithin by the rat jejunum.

Labeled lecithin (32P, 2-3H-glycerol, 1-14C-palmitate) was prepared for studying absorption of lecithin by rat intestine and its incorporation into microsomal and prechylomicron-chylomicron lecithin. Bile fistula rats were perfused intraduodenally with bile salts and lecithin plus a liquid diet. Intestinal samples were obtained after sacrifice and specific activities (DPM/mumol) of isotopes in lecithin were determined. Ratios of specific activities of isotopes were calculated and compared to respective ratios in the original perfusate lecithin. Radioactivity rapidly appeared in jejunal lecithin following perfusion. When specific activities of isotopes in prechylomicron-chylomicron lecithin were compared to those in microsomal lecithin, specific activities were always greater in prechylomicron-chylomicron lecithin. Analysis of ratios of specific activities of isotopes in jejunal lecithin showed that the ratios were nearly identical to those in perfusate phospholipid, indicating that the lysolecithin portion of luminal lecithin can be absorbed intact and can then be utilized for jejunal lecithin synthesis.