Biochemical alterations in rat Thiry-Vella fistulas

In order to obtain baseline information on the secretory function of normal rat bowel for our work on intestinal graft ischemia, we studied several biochemical parameters in rat Thiry-Vella fistulas (TVF). TVFs were created in 200-g male Lewis rats (n = 11) using the 25-cm segment of jejunum normally used as a graft in our intestinal transplant model. The stomas were matured primarily and the animals were allowed to recover. The TVFs were flushed at 0, 6, and 24 h and then daily for up to 21 days with 12 mL normal saline solution. The effluent was collected and analyzed for total protein (TP), secretory phospholipase A2 (sPLA2), intestinal fatty acid binding protein (I-FABP), lactate dehydrogenase (LDH), and N-acetylglucosamine (NAGA). TP content was 0.12 +/- 0.01 mg/mL up to 48 h, then gradually increased and stabilized at 0.39 +/- 0.05 mg/mL at day 21. By sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), one major protein band was identified in the low-molecular-mass range (15 kD), consistent with I-FABP and sPLA2. Secretory PLA2 levels decreased over the first 4 days to a low of 115 +/- 24.8% hydrolysis/min/fraction, then gradually rose to a plateau at approximately 529.76 +/- 88.36% hydrolysis/min/fraction by day 18. I-FABP levels rose rapidly from 0 ng/mL at 2 h to 900 +/- 250.0 ng/mL at 6 h and approximately 3000 +/- 304.9 ng/mL by day 14. LDH levels at 2 h and 48 h did not differ, with 0.03 +/- 0.004 and 0.03 +/- 0.005 optical density units (OD)/min/mL, respectively. NAGA levels were 0.07 +/- 0.05 OD/h/mL at 2 h and rose to 0.14 +/- 0.04 OD/h/mL at 48 h. These data suggest that after an early equilibration period, biochemical secretion into the lumen of normal rat bowel reaches a state of equilibrium, and therefore appears to reflect the baseline biochemical status of the bowel. Some of these levels are not negligible as one would expect in "normal" bowel. This information should prove extremely helpful as a baseline study of abnormal conditions of the intestine, such as ischemia or rejection.

Modification of disaccharidase activity measurement in rat bowel

This study describes a modification of the existing disaccharidase assay in rat small bowel in which whole bowel, rather than mucosa, is utilized. In addition, the use of total vs. specific activity as a more accurate unit of measurement of disaccharidase activity is discussed.

Secretory event in intestinal grafts during preservation ischemia

BACKGROUND

Ischemia triggers secretion of proteins from the intestine, including type II secretory phospholipase A2 (sPLA2). This "secretory event" was studied in intestinal grafts during the first few hours of preservation by measuring total protein, sPLA2, and other enzymes in the UW preservation solution over time. The effect of PX-13, a PLA2 inhibitor, was also studied.

MATERIALS AND METHODS

Twenty-five centimeter intestinal grafts were harvested from Lewis rats, flushed, and preserved in UW solution +/- PX-13 at 4 degrees C. UW samples from 0 to 48 h (n = 5 each) were analyzed for total protein, sPLA2, lactate dehydrogenase (LDH), N-acetylglucosamine (NAGA), and lysozyme. Nonpreserved grafts were homogenized in PBS as tissue controls. Standard biochemical methods were used for all assays.

RESULTS

Total protein increased rapidly by 5 min, continued to rise more slowly until 30 min, and then stabilized. The most significant increase in sPLA2 activity occurred between 90 and 180 min. NAGA increased most markedly between 30 and 180 min, while LDH increased in the first 30 min, although the level of both enzymes was negligible compared to tissue enzyme. Lysozyme levels were minimal at all times. PX-13 decreased sPLA2 activity markedly at all time points.

CONCLUSION

Total protein levels increased before sPLA2, suggesting that sPLA2 may be secreted in response to other proteins or enzymes released even earlier during preservation (e.g., cytokines). These elevations do not appear to be caused by cell death. Phospholipase A2 secretion may be blocked, and this may greatly improve the outcome of intestinal preservation.