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SUMMARY Short loops of dog small intestine, filled with a buffered glucose solution, were subjected to one hour's total ischaemia by clamping the corresponding mesenteric artery and vein as well as the intestinal wall at each end of the loop. Immediately after the ischaemic period and 24 hours later, their functional capacity, together with that of neighbouring control loops, was determined by studying the absorption of phenylalanine and f-methyl-glucoside in vitro and by measuring the levels of Na+-K+-ATPase in the mucosa. The release of lysosomal enzymes after the ischaemia was studied by gauging the levels of acid phosphatase in the venous blood draining the ischaemic loop. The state of the mucosal microcirculation was investigated by injection of indian ink into the mesenteric artery after removal of the loop.Immediately after ischaemia, considerable structural damage was observed in the intestinal mucosa, with desquamation of the villous tips, oedema, vascular stasis, and haemorrhagic infiltration in the lamina propria. No dye was observed in the mucosal capillaries. All transport capacity was abolished, but ATPase levels were unchanged. A significant release of lysosomal enzymes into the venous blood was noted.One day later structural and functional recovery was complete, and vascularization of the villous core was restored.The small intestine is notoriously sensitive to ischaemia (Rausis and Robinson, 1972;Robinson, 1972): functional and morphological damage has been observed in rats (Robinson, Antonioli, and Mirkovitch, 1966) glucose-containing buffer during the period of ischaemia, since this procedure has been shown to have a beneficial effect in restricting ischaemic deterioration (Robinson et al, 1966;Chiu, Scott, and Gurd, 1970b

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Summary.The functional and structural characteristics of the ileal remnant of rat intestine were examined four weeks after 45%, 70% or 95% proximal resection.The increase in villus height in the ileal remnant had already reached its maximum after a resection of 45%, whereas a further increment in the length of the crypts occurred after 70% resection. There was an increase in the number of enterocytes per unit length of villus and a rise in the DNA content per unit weight of mucosal scrapings, which testifies to the development of mucosal hyperplasia in this situation.The specific activities of sucrase, measured biochemically, and of nonspecific esterase, determined histochemically, were reduced in proportion to the extent of the resection. Similarly, the uptakes of L-phenylalanine and of fl-methyl-D-glucoside by intestinal rings in vitro were progressively diminished in the ileal remnant.There was an increase in the rate of disappearance of glucose from a perfused loop in vivo, when expressed in terms of unit intestinal length. Galactose absorption remained unchanged, but when expressed in terms of unit dry tissue, was significantly reduced, in agreement with the diminished transport of both amino-acids and monosaccharides in vitro.