ISOLATED SMOOTH-MUSCLE CELLS FROM HUMAN C OLON - CYTOPHYSIOLOGICAL STUDY

Gross normal specimens of human distal colon were obtained at operatio n for cancer. Smooth muscle cells were separated from internal and ext ernal layers of the muscularis. They were dissociated by digestion wit h collagenase, isolated and concentrated by successive centrifugations . Colonic smooth muscle cell contraction was measured using various co ncentrations of carbamylcholine (10(-9) to 10(-4) M); relaxation was t ested using atropine (10(-9) to 10(-4) M) on colonic smooth muscle cel ls pre-contracted by carbamylcholine. Compared with previous descripti ons, human smooth muscle cells were smaller than in other species with an enlarged distribution of cell size (30 mum to 150 mum in length). Significant dose-response curves were obtained for both carbamylcholin e and atropine. However, 3 original points characterized human colonic smooth muscle cells: a) the cells isolated from the internal layer we re significantly more sensitive than those isolated from the external layer (10(-9) M vs 10(-7) M); b) for the muscle cells isolated from bo th the internal and external layers, small colonic smooth muscle cells were significantly more sensitive. On the other hand, these cells wer e shown to be located near conjonctive septae, and intramural plexuses ; c) analysis of contraction curves demonstrated a more efficient resp onse for colonic smooth muscle cells of the internal layer than for th ose of the external layer of the muscularis.