STUDIES ON ISOLATED SMOOTH-MUSCLE CELLS .5. CALCIUM AND CAFFEINE CONTRACTION OF SINGLE SMOOTH-MUSCLE CELLS ISOLATED FROM TAENIA-COLI OF GUINEA-PIG

Single smooth muscle cells were isolated from tenia coli of guinea pig, and Ca- and caffeine-contraction was studied. The degree of contraction of the single cells by Ca under the depolarized condition was dependent on the Ca concentration but the sensitivity of the cells to Ca was less than that of intact tissue. Cells which were responsive to Ca were 56% of the cells examined. Subsequent caffeine application to the cells resulted in contraction of 85% of the single cells. These single cells examined in this experiment were not stained by trypan blue. The results indicated that, during isolation, certain trigger mechanism to produce contraction by exogenous Ca was hindered in a half of the cell preparation.