The formation of radiolabeled N1- and N8-acetylspermidine in various rat organs following [14C]spermidine administration.

To detect the in vivo formation of acetylspermidine, three female Sprague-Dawley rats were injected intravenously with 20 muCi of [14C]spermidine. Twenty-four hours after the injection of the radiolabel, the kidneys, liver, lungs, pancreas, small intestine, spleen, stomach and thymus were removed under Halothane anesthesia. High performance liquid chromatography (HPLC) of the pooled radiolabeled extracts from each tissue demonstrated the presence of a 14C-labeled material which co-chromatographed with an acetylspermidine standard. Thin layer chromatography (TLC) of the HPLC eluent demonstrated the presence of both radiolabeled N1- and N8-acetylspermidine in the tissues. Concentrations of labeled acetylspermidine ranged from 0.27 to 1.9% of the total tissue radiolabel. The N1-to N8-acetylspermidine ratio in tissues ranged from approx. 5 to 1 in the thymus to 1.5 to 1 in the liver.