Search

Cholesterol, long-chain fatty acids, and fat-soluble vitamins are absorbed mainly in the upper small intestine and bile acids in the terminal ileum. This study determined the consequences of ileal autotransplantation on cholesterol metabolism, plasma fatty acids, and vitamin A absorption.Plasma lipids, cholesterol precursors, plant sterols, cholestanol, fatty acids, vitamin A absorption, and animal growth were studied for 3 months after transection (n = 5), jejunal (50%) resection (n = 7), jejunal (50%) resection combined with orthotopic ileal autotransplantation (n = 7), and enterectomy (n = 7).Cholesterol precursor to cholesterol proportions in plasma (reflect cholesterol synthesis) remained unchanged after transection and jejunal resection. The plasma plant sterol proportions (reflect cholesterol absorption) and retinol absorption increased after transection and less significantly after jejunal resection, whereas plasma fatty acid compositions were virtually unchanged. Transplantation of ileum and enterectomy amended up to sixfold the precursor proportions (p0.05 versus transection or jejunal resection) and impaired body weight gain. The plant sterol proportions, vitamin A absorption, and plasma cholesterol levels, respectively, were significantly (p0.05) decreased after transplantation when compared with those of the transected control group but remained markedly higher than those in the enterectomized group. Linoleic acid was significantly (p0.05 versus transection) decreased, whereas monoenoic fatty acids and eicosatrienoic acid were increased (p0.05 versus jejunal resection) in plasma lipids.These results indicate that autotransplantation of ileum in pigs that have undergone jejunectomy impairs sterol, essential fatty acid, and vitamin A absorption so that plasma cholesterol levels decrease despite markedly increased cholesterol synthesis and that these changes clearly exceed those found after jejunal resection alone.

Cholesterol absorption occurs primarily in the upper small intestine. Our aim was to assess absorption of cholesterol during ileal adaptation after proximal small intestinal resection. In vivo absorption and elimination of cholesterol, plasma cholesterol, cholesterol precursors, and plant sterols were related to intestinal morphology and transit 4 (n = 5), 8 (n = 5), and 14 (n = 5) weeks after a 75% proximal resection of porcine small intestine, and compared to preoperative (n = 5) and transected (n = 5) control animals. Fractional cholesterol absorption, the daily amount of cholesterol absorbed, plasma cholesterol, and plant sterol to cholesterol proportions were significantly (P < 0.05 or less) decreased, whereas fecal loss of cholesterol as neutral steroids, less so as bile acids, plasma cholesterol precursor proportions, and ileal mass and villus height were significantly increased (P < 0.05 or less) after 8 weeks of the resection. Cholesterol absorption efficiency, decreased by the resection, was gradually increased from 5.4 +/- 2.2 to 26.9 +/- 3.9% during the 14 postoperative weeks (P < 0.0001) simultaneously with a 46% increase in villus height compared with transection (P < 0.0001), but absorption remained still below control levels (80.4 +/- 2.5%, P < 0.0001). In resected and control animals, villus height correlated positively with cholesterol absorption efficiency (r = 0.85, P < 0.0001; r = 0.76, P = 0.01) and plasma plant sterol proportions (r = 0.94-0.95, P < 0.0001; r = 0.78-0.85, P < 0.008), respectively. In conclusion, after massive proximal small bowel resection, adaptation of intestinal cholesterol absorption efficiency occurs in the distal ileum closely parlleling villus hypertrophy.