Total ischaemia of loops of dog colon was induced by clamping all afferent arteries and the colonic wall for different periods of time.Net sodium transport across the mucosa is abolished after one hour's ischaemia, but Na(+)-K(+)-ATPase levels in microsomal suspensions from the mucosa only fall significantly after two hours' ischaemia. Studies on the functional and morphological recovery of colons subjected to three hours' ischaemia have disclosed an extremely heterogeneous response among the 24 dogs used. Although all parameters were non-existent 24 hours after the intervention, one colon revealed a morphological and functional recovery one week after the operation, whilst two, three, and three out of six recovered after two, three, and four weeks respectively. There was a good correlation between the functional and macroscopic appearance of these recovered loops, though histologically various degrees of disorganization of the mucosa were observed. Among the loops that had no function, there was also a considerable variation in their microscopic structures. The level of Na(+)-K(+)-ATPase in the mucosa was found to be a faithful indicator of the functional state of the tissue, and could be closely correlated with the morphological findings.

Adenosine Triphosphatases↗

PubMed1972

The recovery of function and microcirculation in small intestinal loops following ischaemia.

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 beta-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 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.

Acid Phosphatase↗

PubMed1972