Autoradiographic study of the distribution and cellular uptake of (14C) - streptozotocin in the rat.

The distribution and cellular accumulation, in the rat, of three specifically 14C-labelled forms of streptozotocin were investigated. A significant pancreatic accumulation of radioactivity was observed with (3' -methyl-14C)-streptozotocin only. Autoradiographic studies revealed high levels of bound radioactivity in the islet tissue following the administration of (3 -methyl-14C)-streptozotocin whereas much lower levels of radioactivity were detected in the pancreatic tissue following the administration of either (1-14C)-streptozotocin or (2' -14C)-streptozotocin. In the pancreasea, the amount of radioactivity bound to islet tissue was always significantly higher than that bound to acinar tissue. In addition to the islet tissues, the kidney cortex showed a very high level of bound radioactivity after the administration of (3' -methyl-14C)-streptozotocin. The results suggest that streptozotocin is rapidly metabolised by the rat. The apparent specificity for the accumulation of radiolabel from (3' -methyl-14 C)-streptozotocin suggests that a metabolite derived from the methyl bearing ureido side chain of the drug may be specifically involved in the induction of tissue damage and the consequent development of diabetes.