title: The fate of [14C]streptozotocin in nicotinamide-pretreated mice: observations on pancreatic islet radioactivity and urinary N1-methyl-14C]nicotinamide-excretion.
abstract: A high labelling of the pancreatic islets was found 3 and 24 h after a diabetogenic dose of [14C]streptozotocin to mice in which the acids islet injury had been prevented by nicotinamide-pretreatment. In non-pretreated [14C]streptozotocin-injected mice, a much lower radioactivity was observed in the pancreatic islets; at 3 h and at 24 h, there was no detectable radioactivity in the islets. No evidence was found to indicate that nicotinamide-pretreatment had any marked effect on the uptake or retention of radioactivity in other tissues. N1-[methyl-14C]nicotinamide was not found in the urine of non-pretreated [14C]streptozotocin-injected mice. When the animals were pretreated with nicotinamide, N1-[methyl-14C]nicotinamide was detected in the urine, but this represented only a small fraction of the injected radioactivity and of the excreted N1-methylnicotinamide. This result does not support the hypothesis that the disturbance of the NAD-metabolism, which streptozotocin causes, is due to a methylation of nicotinamide.
mesh_terms: D000818:Animals; D002250:Carbon Radioisotopes; D005260:Female; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D008745:Methylation; D051379:Mice; D009536:Niacinamide / Q000031:analogs & derivatives* / Q000378:metabolism / Q000652:urine; D013311:Streptozocin / Q000378:metabolism* / Q000494:pharmacology; D014018:Tissue Distribution
chemical_list: D002250:Carbon Radioisotopes; D009536:Niacinamide; D013311:Streptozocin; C024058:N(1)-methylnicotinamide