ADAPTATION OF CHOLESTEROL ABSORPTION AFTER PROXIMAL RESECTION OF PORCINE SMALL-INTESTINE

Cholesterol absorption occurs primarily in the upper small intestine. Our aim was to assess absorption of cholesterol during ileal adaptatio n after proximal small intestinal resection. In vivo absorption and el imination 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 resectio n 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 pl ant 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 o r less) after 8 weeks of the resection. Cholesterol absorption efficie ncy, 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) si multaneously with a 46% increase in villus height compared with transe ction (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 propo rtions (r = 0.94-0.95, P < 0.0001; r = 0.78-0.85, P < 0.008), respecti vely. In conclusion, after massive proximal small bowel resection, ada ptation of intestinal cholesterol absorption efficiency occurs in the distal ileum closely paralleling villus hypertrophy.