Alkylation of Rat Liver RNA by Cyclic N-Nitrosamines In Vivo2

Abstract

The possibility that the carcinogenic action of cyclic N-nitrosamines is related to their ability to form alkylating agents in vivo was investigated. Three nitrosamines, nitrosopyrrolidine, nitrosomorpholine, and nitrosopiperidine, were labeled with tritium and injected into rats. The rats were killed after a suitable time, the livers were homogenized, and a preparation of RNA was made from each. All the RNA preparations contained tritium. The chromatographic profiles (on an ion-exchange column) of the acid hydrolysates of each RNA revealed the presence of an abnormal, labeled base between guanine and adenine. This base always appeared to be the same. The abnormal base derived from nitrosomorpholine was identified as 7-methylguanine by mass spectrometry.