Water content and inulin space of circular smooth muscle of cat intestine were determined to be 810 [plus or minus] 2 g/kg wet weight and 101 [plus or minus] 17 ml/kg wet weight, respectively. Total K, Na, and C1 were determined and intracellular concentrations of K, Na, and C1 were calculated to be 108 [plus or minus] 6, 65 [plus or minus] 5 and 77 [plus or minus] meq/kg cell H2O; respectively.