A m c t I J TLC and liquid scintillation spectrometry were used to determine the identities and relative quantities of aspirin and its metabolites in the gastric juice, blood plasma, rumen (nonglandular portion), and corpus (glandular portion) of the rat stomach 4 min. after the oral administration of aspirin-7-1.C.It was found that aspirin and salicylic acid are the major components in the gastric juice, blood plasma, and rumen and corpus tissues. Trace levels of a compound with an R, value corresponding to that of salicyluric acid was found in the fluids and tissues analyzed. No glucuronide conjugates of salicylic acid or polyhydroxy metabolites of aspirin were found. The level of salicylic acid was fourfold higher in the corpus tissue than in the rumen tissue.Keyphrases 0 Aspirin, radiolabeled-metabolism in rumen and corpus tissues, during first 4 min. after oral administration, rats, TLC and liquid scintillation spectrometric determination of metabolites 0 Salicylic aciddetermination as metabolite in rumen and corpus tissues of rat 4 min. after oral administration of radiolabeled aspirin 0 Metabolism-radiolabeled aspirin, determination of metabolites in rat 4 min. after oral administration, rumen and corpus tissues It is well known that gastric irritation leading to the production of lesions and occult bleeding occurs in laboratory animals and man following oral administration of salicylates (1,2). Aspirin has been reported (3,4) to produce gastric lesions in the corpus portion of the albino rat when administered orally at a level of 50 mg./kg. of body weight.The production of gastric lesions following intravenous administration of salicylates was reported by Hurley and Crandall (9, Grossman et al. (6), and Morns (7), but the lesions were much less severe than those produced by oral administration.Although systematic mechanisms have been proposed to explain the production of lesions, the present authors felt that the initial mechanism of lesion formation might be a localized chemical phenomenon since previous studies (3) had shown that some rats develop gastric lesions in the corpus (glandular) portion of the stomach within 5 min. after administration of aspirin.. Lesions have not been produced in the rumen (nonglandular portion) under the same experimental conditions. It, therefore, became of interest to identify and compare the relative quantities of aspirin and/or its metabolites in the rumen and corpus tissues of the rat shortly after administration of a~pirin-7-~'C.
MATERIALS AND METHODSRadiochemical purity of aspirin-F1C was established by TLC in conjunction with autoradiography and liquid scintillation spectrometry. The chemical identity and purity of standards of aspirin and its metabolites were established by melting point and TLC.Four d e albino laboratory rats'. weighing between 100 and 200 g., were fasted for 12 hr. prior to the ad~nhistration of aspirin-7-"c but were allowed water ad libitum until the time of drug administration.Drug Admlalstntlon-To achieve the most rapid and uniform absorption,...
