To quantitate surface hydrophobicity of the intestine, we measured contact angles formed with water droplets in multiple regions of rabbit intestine at varying ages (suckling, weanling, and adult) and after dinitrochlorobenzene-induced colitis. Contact angles were measured using novel methods: axisymmetric drop-shape analysis-contact diameter for contact angles less than 90 degrees and axisymmetric dropshape analysis-maximum diameter for contact angles greater than 90 degrees. To determine whether mucus was present on the surface of intestine used, indirect immunofluorescence was performed using antibody specific to goblet cell mucin. To confirm that intestinal mucus could be responsible for the physical properties of surface mucosa, surface tensions of mucus prepared from distal ileum, distal colon, and inflamed distal colon of adult rabbits were measured by axisymmetric drop-shape analysis on pendant drops. Contact angles of adult small intestine [duodenum, 38.0 +/- 11.2 degrees (SD); jejunum, 44.0 +/- 22.9 degrees; ileum, 56.4 +/- 23.3 degrees] were less than proximal colon (93.2 +/- 6.7 degrees; P less than 0.05) and distal colon (86.4 +/- 24.2 degrees; P less than 0.05). Contact angles on proximal colon from suckling rabbits (53.2 +/- 8.4 degrees) were less than both weanling (93.2 +/- 23.3 degrees; P less than 0.05) and adult rabbits (93.2 +/- 6.7 degrees; P less than 0.05). Contact angles on inflamed adult distal colon (54.7 +/- 20.6 degrees) were decreased from values on normal distal colons (86.4 +/- 24.2 degrees). Indirect immunofluorescence demonstrated that mucin was present in both vacuoles of goblet cells and on the colonic surface.(ABSTRACT TRUNCATED AT 250 WORDS)
Drop shape analysis for determination of dynamic contact angles by double sided elliptical fitting method