SECRETORY PHOSPHOLIPASE A(2) LEVELS IN RAT SMALL-BOWEL

Preliminary studies on ischemia/reperfusion injury in transplanted sma ll bowel grafts showed that secretory phospholipase A(2) (sPLA(2)) may play a substantial role by breaking down membrane phospholipids. This study sought to determine the normal values of sPLA(2) in the rat sma ll bowel as a function of site and length as a baseline for future stu dies. The entire small bowel of male Lewis rats (200 g) was flushed wi th normal saline to eliminate solid contents. In group 1, the entire s mall bowel was divided into 5-cm segments (numbered 1-9), which were s nap frozen and processed the same day for sPLA(2). In group 2, a 25-cm segment of bowel (corresponding to segments 2-6 in group 1) was harve sted from each animal, snap frozen, and immediately processed for sPLA (2). To assess the effect of bowel storage on enzyme content group 3 a nd group 4 grafts were stored for 7 and 14 days, respectively, at -85 degrees C prior to processing. All samples were homogenized in buffer extracted with H2SO4, and assayed for sPLA(2) activity using [1-C-14]o leate-labeled autoclaved Escherichia coli as substrate. Results were a nalyzed statistically by ANOVA. sPLA(2) activity rose from 85.46 +/- 1 4.46% hydrolysis/min fraction(-1) in segment 1, to 476.38 +/- 176.75% hydrolysis/min fraction(-1) in segment 9. The increase was linear and statistically significant (p < .0001). There was no significant differ ence in enzymatic activity between groups 2, 3, and 4. Group 2 activit y was 263.02 +/- 43. 74% hydrolysis/min fraction(-1). This value was n ot statistically differentfrom the mathematically calculated mean of s egments 2-6 in group 1 (237.75). The results show that (1) sPLA(2) act ivity increases predictably with distance from the ligament of Treitz, (2) storage at -85 degrees C does not affect sPLA(2) activity and (3) 25-cm grafts may be evaluated in tote with reproducible baseline enzy me activity. Given the variability of enzyme activity along the course of the rat small bowel, it is imperative that exact location be ident ified in any studies evaluating sPLA(2) activity.