Hybrid information provided by the 14C-aminopyrine breath test studies with 14C-monomethylaminoantipyrine in the guinea pig
- 1 January 1980
- journal article
- research article
- Published by Springer Nature in Naunyn-Schmiedebergs Archiv für experimentelle Pathologie und Pharmakologie
- Vol. 313 (2), 175-178
- https://doi.org/10.1007/bf00498577
Abstract
N-Demethylation of 14C-aminopyrine (14C-AP), labelled at the methyl groups of the tertiary amino group, yields H14CHO and 14C-monomethylaminoantipyrine (14C-MMAAP) which also undergoes N-demethylation, however, at a slower rate as measured in hepatic microsomes. As after intraperitoneal application to male guinea pigs of 14C-AP (75 mg/kg; 50 μCi/kg), exhalation rate of 14CO2 declines in a biphasic manner, the hypothesis was tested whether the terminal part might reflect N-demethylation of MMAAP. The application of 14C-MMAAP (70 mg/kg; 10 μCi/kg), resulted in monophasic curves of 14CO2 exhalation rate. Their half lives were, however, longer than terminal half lives obtained after 14C-AP. Obviously, this terminal phase does not represent 14CO2 formation from the metabolite MMAAP only, but 14C-AP might still contribute to 14CO2 production. Confirmation was obtained by HPLC determination of AP and MMAAP in serum after injection of AP. Shortly after injection, high concentrations of AP and low ones of MMAAP were found in blood from the portal vein and systemic circulation. Thus, initial parts of 14CO2-exhalation rate curves reflect predominantly AP metabolism whereas later phases provide hybrid information.This publication has 3 references indexed in Scilit:
- Inhibition of aminopyrine demethylation and binding to cytochrome P-450 by its main metabolites in rat liver microsomes [proceedings].1980
- EXPIRATORY MEASUREMENT OF MAXIMAL AMINOPYRINE DEMETHYLATION INVIVO - EFFECT OF PHENOBARBITAL, PARTIAL-HEPATECTOMY, PORTACAVAL-SHUNT AND BILE-DUCT LIGATION IN RAT1976
- The colorimetric estimation of formaldehyde by means of the Hantzsch reactionBiochemical Journal, 1953