Preferential oxidation of fatty acids by rat small intestine.

In a previous study from this laboratory it was shown that mitochondria can be harvested from rat small intestinal epithelial cells and that these mitochondria show intact oxidative phosphorylation [ 11. Further studies [2] showed that the isolated mitochondria are able to oxidize octanoate and palmitate completely to CO? and HzO, whereas earlier studies [3] showed that 3-hydroxybuty rate is also a substrate for these mitochondria. It is the purpose of the present paper to extend these studies with observations carried out with isolated rat small intestine, perfused in vitro with glucose and/or long-chain fatty acids, octanoate or 3-hydroxybutyrate. The present experiments are carried out with small intestines isolated from fed male white rats (250-300 g). The animals were operated under Nembutal narcosis. The operation was carried out in principle as described by Gerber [4] . The rectum was cut between two ligatures and mobilized, followed by a complete coecum and large bowel resection. The duodenum was opened about 5 cm from the stomach and a cannula inserted so that the small intestine could be rinsed with 50 ml warm saline. After the passage of air the duodenum and the terminal ileum were tied. The abdominal aorta was prepared free from the A. coeliaca until the bifurcatio iliaca. Loose ligatures were placed around the aorta, distal and proximal from the A. mesenterica superior, whereas the A. renalis dextra was tied. Loose ligatures were also placed under the V. porta and the V. mesenterica superior, after tying the V. gastricuduodenalis and V. lienalis. Then the