0000000000726321
AUTHOR
H. P. A. Illing
showing 3 related works from this author
Interrelationship between demethylation of p-nitroanisole and conjugation of p-nitrophenol in rat liver
1973
The metabolism of p-nitroanisole (pNA) and p-nitrophenol (pNP) was studied in isolated rat livers perfused with a hemoglobin-free medium. The activity and viability of the surviving organ was tested by recording pH, “arterial” and “venous” oxygen tension as well as the disappearance of added pNP. pNA is converted to its primary metabolite pNP which, in turn, is excreted into the perfusion medium as conjugates. The coordination of pNA oxidation and the conjugation reactions of pNP were investigated. When 50 μM pNA is added as substrate 0.4±0.1 nmoles×ml−1×(g liver)−1 are excreted as pNP-glucuronide and 3.5±0.2 nmoles×ml−1×(g liver)−1 as the sulphate within 90 min. When pNP itself (50 μM) is …
Kinetic experiments on the synergistic effect of NADH on microsomal drug oxidation.
1974
Abstract1. The synergistic effect of NADH on the NADPH-dependent mixed function oxidation of p-nitroanisole and hexobarbital can be measured both photometrically and by following the substrate-induced oxygen consumption. The increase in reaction rate is about 50% and lasts as long as NADH is present in the microsomal suspension.2. The oxidation of added NADH is increased by hexobarbital, ethylmorphine and SKF 525-A. Lineweaver-Burk transformation of the NADH oxidation rates yields straight lines for xenobiotic substrates suggesting Michaelis constants similar to those obtained from metabolic experiments. NADH oxidation in the absence of NADPH is about half as rapid as in its presence.3. Som…
Measurement of substrate-induced oxygen uptake during microsomal drug oxidation using a gold micro-electrode.
1975
1. A resin-coated gold micro-electrode has been used for polarographic determination of oxygen concentration in liver microsomal suspensions from phenobarbital-pretreated rats. 2. The rate of oxygen uptake on addition of an NADPH-regenerating system and the rate after addition of various substrates of the mixed function oxidase system were measured. The rate of oxygen uptake was faster in the presence of substrate than in the presence of NADPH alone. 3. Kinetic constants (Km and V max) for biphenyl, hexobarbital, ethylmorphine, naphthalene and SKF 525-A measured by this technique compare favourably with those obtained either by measurements of NADPH oxidation, or chemical measurements of su…