Abstracts
1997 Digestive Disease Week

Serum D(-)-lactate as a marker of intestinal ischemia.

M Gonze*, M Murray*, G Kessler**, P Olson**, C Cobb*. Department of Surgery* and Pathology**, Allegheny General Hospital, Allegheny University of the Health Sciences, Pittsburgh, PA.

D(-)-Lactate (DL) is a bacterial product produced within animal and human intestines. DL can pass through the portal system, through the liver unmetabolized, and into the peripheral blood when the bowel is injured. DL has recently been found to be a marker of irreversible intestinal ischemia in both rats and humans. However, it is not known if DL is elevated in reversible ischemia or if DL returns to baseline once the ischemia is reversed. Therefore, this project evaluated DL levels in a rat model of reversible intestinal ischemia. Twenty-three rats underwent one hour superior mesenteric artery (SMA) occlusion with an atraumatic vascular clamp followed by SMA reperfusion for 6 hours. Blood DL levels were determined prior to SMA occlusion and then after 2 hours and 6 hours of reperfusion. The rats were sacrificed at 6 hours. The terminal ileum and the most damaged segment of small bowel were removed and examined histologically by pathologists blinded to DL levels. Histologic evaluation divided the rats into two groups, reversible or irreversible damage. The DL results (mean ± SD) for the two groups are summarized:

               D(-)-LACTATE LEVEL (µg/ml)
                      Time=Initial    Time=2 Hours    Time=6 Hours
Reversible (n=13)      2.66±1.2        46.32±14.7      12.01±3.6
Irreversible (n=10)    3.35±0.6        57.91±11.0      63.42±5.9

Repeated measures ANOVA followed by the student's t-test for significance was performed on the mean DL levels. In the reversible group, the DL level significantly increased after 2 hours of reperfusion (p<0.0005) and then significantly declined after 6 hours (p<0.0005) of reperfusion. Rats in the irreversible damage group had a significant rise in the DL levels between the baseline and the 2 hour samples (p<0.0005), but the levels did not decline at 6 hours. D(-)-Lactate is significantly elevated in reversible mesenteric ischemia and then declines toward baseline values when the ischemia is reversed. This may be beneficial in differentiating infarction from reversible ischemia.