LAMININ STIMULATES RAPID EPITHELIAL RESTITUTION OF RABBIT DUODENAL MUCOSA IN-VITRO

Background: This study investigated the effect of the basal lamina con stituents fibronectin, collagen IV, and laminin on epithelial restitut ion of rabbit duodenum in vitro. Methods: Rabbit duodenal mucosal shee ts were mounted in Ussing chambers, luminally exposed to 10 mM HCl for 10 min, and incubated with buffer or luminal buffer containing 25-100 mu g/ml of collagen IV, fibronectin, laminin, or polyclonal antisera directed against these proteins (diluted 1:50-1:20) for 3 h. Resistanc e was calculated from potential difference and short-circuit current. Mucosal damage was assessed by morphometry on hematoxylin- and eosin-s tained sections. Results: Acid exposure caused a 40% drop in resistanc e (119 +/- 5 versus 71 +/- 5 Ohm . cm(2) before versus after injury; P < 0.05, n = 6) and mucosal damage of 58 +/- 4% (n = 6). Three hours a fter injury resistance was 102 +/- 6, 117 +/- 4, and 48 + 5 Ohm . cm(2 ) in the control, laminin, and anti-laminin groups, respectively. Furt hermore, 36 +/- 2%, 16 +/- 2%, and 64 +/- 5% of the mucosa was damaged in the control, laminin, and anti-laminin groups, respectively, 3 h a fter injury (P < 0.05 versus controls). Laminin promoted epithelial wo und closure by stimulation of enterocyte migration, which was inhibite d by anti-laminin. Fibronectin, collagen IV, anti-fibronectin, and ant icollagen IV did not impair restitution. Conclusion: Our results show that laminin promotes electrophysiologic restoration and epithelial re stitution of rabbit duodenum in vitro. We therefore suggest that lamin in plays an important part in the orchestration of epithelial integrit y and barrier function.