Different responses of apolipoprotein A-I, A-IV, and B gene expression during intestinal adaptation to a massive small bowel resection in rats

Gene expression of apolipoproteins (ape) A-I, A-IV, and B, the predominant protein components of chylomicrons, was investigated in the residual ileum after a massive small bowel resection in rats. A Northern blot analysis showed that the ape A-IV mRNA level, but not the ape A-I and B mRNA levels, in the ileum was significantly higher in the resected rats than in the sham-operated rats 24h and 2 wk post-surgery. RT-PCR coupled with a primer extension assay revealed that the ape B-48 mRNA/apo B-100 mRNA ratio, i.e., ape B mRNA editing, in the ielum was unchanged by the resection. It is thus concluded that, among the major intestinal apolipoproteins, ape A-IV is the only one whose gene expression is influenced by loss of the proximal intestine.