El surfactante colónico y la hidrofobicidad de superficie. Papel en la barrera mucosa del colon

by Sánchez García, José Luis

Gastrointestinal mucosal barrier, formed by surfactant, mucus and epithelium, separates the digestive tract lumen from the internal milieu. The surfactant, made up of phospholipids, establishes mucosal surface properties. Previous studies in this barrier have been carried out in animal stomachs. Aims. Study the surface properties in the human colonic mucosal. Materials and Methods. Samples of human colonic and rectal mucosal obtained from surgical pieces have been processed in modified physiologic solution (SF), with epidermal growth factor (EGF), prostaglandin E2 (PGE2), diclofenac (45 mg and 90 mg) and indomethacin (same dose) being determined with the goniometer the contact angle (q) to measure the hydrophobicity. Phospholipid proportions are determined from mucosal homogenized. Statistical analysis: Mann-Whitney test, Kruskal-Wallis test, Spearman correlation coefficient, Student test and ANOVA. Values of p<0.05 were considered statistically significant. Results. 134 mucosal samples were obtained from 74 patients. In the group control q was 39.52º; in the group processed with SF, 42.29º (p < 0.0001). The samples were divided in those of patients with pathological antecedents (n=47, q=39.34) and those of patients without antecedents (n=87, q=39.64º) (p=0.01). This second group was divided in: disorders of lipid metabolism (40º), chronic bronchitis (39.58º), heart disease (39.30º), diabetes mellitus (39º) and hypertension (39º) (p=0.01). The process with EGF (49.44º) and PGE2 (47.32º) determined differences (p < 0.001) and also the group SF (p < 0.0001). The process with diclofenac (35.43º) and indomethacin (35.97º) determined differences (p < 0.001) and also the group SF (p < 0.0001); in both of them, the duplication of the dose increases the reduction (35º) and (34.53º) (p < 0.0001). Colonic division in 7 segments: cecum (39.26º), ascending (39.53º), proximal transverse (39.26º), distal transverse (39.46ª), descending (39.52º), sigmoid (39.70º) and rectum (39.6º), didn't set differences (p=0.1) . In four sectors: right, transverse, left and rectum, neither (p>0.1). Correlation coefficient between q and surfactant proportion (phospholipids mM / tissue g): cecum (200.3), ascending (203.1), transverse proximal (210.4), transverse distal (212), descending (217.5), sigmoid (223.4) and rectum (226.2), was r=0.7207 (p=0.08). Conclusion. Hydrophobicity in the human colonic mucosal surface decreases by the action of the NSAID. This property increases by the action of the cytoprotectors. In different diseases the hydrophobicity is decreased. Hydrophobicity is smaller in colonic proximal tracts and bigger in distals. The correlation between this property and the proportion of phosopholipids is direct and it is related with the function in each segment of the colon: water absorption in proximal tracts and fecal conduction in distal tracts.