Serum cytosolic β-glucosidase elevation and early ischemic injury to guinea pig small intestine

Background. The lack of an early, sensitive marker for intestinal ischemia has led to delay in diagnosis and worsened outcome for patients with acute onset of this condition. Our preliminary studies revealed that guinea pig cytosolic β-glucosidase (CBG) is expressed predominantly in the small intestine, with lower levels in the liver and pancreas and undetectable levels in other organs. Cytosolic β-glucosidase was investigated as a serum marker of small intestinal ischemia in a guinea pig model. Methods. Guinea pigs underwent anesthesia, sham laparotomy, 30 minutes of mesenteric ischemia followed by 6 hours of reperfusion, 6 hours of sustained mesenteric ischemia, or closed-loop small bowel obstruction. Serum samples were assayed for CBG activity. At the conclusion of the ischemia/reperfusion experiments, small bowel samples were assayed for residual enzyme activity, and paraffin sections were graded for the severity of histologic injury. Results. Serum CBG activity rose rapidly after intestinal ischemia with and without reperfusion. Peak enzyme activities were elevated 23-fold for reperfused animals (P < .001) by 4 hours. For nonreperfused animals, peak serum CBG activities reached 29-fold above baseline and were significantly higher than the CBG activities of reperfused animals at 4 hours (P < .01) and at 6 hours (P < .05). Mucosal injury ranged from undetectable to moderate and corresponded in severity with both peak serum enzyme activity and decreased residual activity in the small bowel. In animals subjected to closed-loop obstruction, there was a mean increase of serum CBG of 9.2-fold from 4 to 6 hours after establishment of obstruction (P < .05). Conclusions. In the guinea pig model, CBG is a sensitive marker of ischemic injury caused by arterial occlusion or closed-loop obstruction of the small bowel.