THE ACCUMULATION OF ADENOSINE IN RABBIT INTESTINAL MUSCLE

1 Strips of longitudinal muscle from rabbit intestine accumulated radioactivity when exposed to [ 3 H]‐adenosine. 2 Accumulation of radioactivity was not sodium‐dependent or ouabain‐sensitive, but was reduced by cooling, zero glucose plus bubbling with N 2 , 2,4, dinitrophenol, dipyridamole, hexobendine and lidoflazine. 3 After 7 min exposure to [ 3 H]‐adenosine, the tissue was found to contain radioactive adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP) and adenosine itself in the approximate ratio 13: 6: 4: 1. 4 In the presence of dipyridamole, hexobendine or lidoflazine (each 1 μ m ), the amounts of radioactive ATP, ADP, AMP and adenosine were reduced with the concentration of adenosine not significantly different from controls. 5 It is concluded that energy‐dependent uptake of adenosine does not occur in the longitudinal muscle of rabbit intestine. Adenosine enters the tissue by a passive process and rapidly becomes phosphorylated giving rise to apparently high tissue: medium ratios. 6 The drugs dipyridamole, hexobendine and lidoflazine appear to reduce the accumulation of radioactivity by preventing the formation of adenosine phosphate derivatives.