ELECTROPHYSIOLOGICAL CHARACTERIZATION OF HUMAN DISTAL COLON EPITHELIUM ISOLATED USING A NOVEL TECHNIQUE

Electrophysiological studies of human colonic epithelia traditionally have been hampered by the lack of tissue availability and by poor tiss ue quality. Human colonic epithelium is usually obtained surgically fr om individuals with underlying disease, while surgery itself can injur e or alter the resected tissue. As a result, a wide range in electroph ysiological parameters is reported in previous studies of human coloni c epithelium. Such factors may also account for differences in measure ments between humans and the few other species studied. We therefore d evised a novel and rapid endoscopic technique, endoscopic mucosal rese ction (EMR), that allows for the removal and study of intestinal mucos al epithelium from normal volunteers. Using EMR we rapidly (7.2 +/- 2. 4 min) isolated surgical-sized epithelial sheets from the distal colon (1.4 +/- 0.4 by 1.3 +/- 0.4 cm) that were readily mounted in a 0.64-c m(2) Ussing chamber. We observed stable resistance (289 +/- 30 Omega . cm(2)), potential difference (1.6 +/- 0.6 mV), and I-SC (24 +/- 9 mu A/cm(2)) for at least 90 min, after which all experiments were termina ted. Exposure to carbachol increased I-SC 2.2 +/- 0.5-fold, while fors kolin increased I,, 4.4 +/- 0.5-fold. These data show that the electro physiological characteristics of the human distal colon removed by EMR more closely approximate values reported for other mammals than when removed using other techniques. Thus EMR represents a significant adva nce over traditional techniques for isolating human tissues and will i ncrease the availability of this tissue for future studies.