The electrical and sodium transport characteristics of sutured premalignant mouse colon

Depolarization of the plasma membrane and increased sodium influx have both been suggested as mitogenic signals. Following bowel resection the intestinal suture line has been reported a fertile site for tumor recurrence. Whether alterations in cell surface signaling occur at suture lines has not been previously examined the electrical changes of sodium transport occurring at a suture line in an animal model of large bowel cancer. Forty-eight female CF1 mice underwent colotomies with repair utilizing silk or chromic sutures. Twenty-four mice underwent sham operations to serve as controls. The mice were injected subcutaneously with the carcinogen DMH (1,2-dimethylhydrazine) 20 mg/kg or an identical volume of 0.9% saline for 6 weeks and were sacrificed 1 week after the last injection. The sites of the sutured colotomies or a piece of distal colon from the sham-operated mice were mounted in a modified Ussing chamber and the electrical properties and unidirectional sodium fluxes were measured. The potential difference (pd) across the distal colon was not significantly different in any suture group compared to that in sham-operated controls when treated with saline (pd sham, -2.3 +/- 0.2 mV (mean +/- SEM); silk, -1.7 +/- 0.3 mV, chromic, -1.9 +/- 0.3 mV, P greater than 0.05, unpaired Student t test). The potential difference was significantly lowered in both suture groups compared to sham operated animals after treatment with DMH (pd sham, -2.6 +/- 0.3 mV; silk, -1.5 +/- 0.2 mV, P less than 0.05; chromic, -1.6 +/- 0.4 mV, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)