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Biomedical subjects

H Kitagawa

Publications and source records attributed to H Kitagawa.

At least 649 records · Page 36Linked to original sources
PubMed1977

Stimulative effects of chelating agents, 2,2'-bipyridine and 1,10-phenanthroline, on lipid peroxidation in rat liver microsomes.

Well known lipid peroxidation inhibitors, 1,10-phenanthroline and 2,2'-bipyridine, stimulated microsomal NADPH- and ascorbic acid-dependent lipid peroxidation when low concentrations of these chelating agents were added to incubation mixture. The stimulatory effects of the chelating agents on lipid peroxidation were enhanced when ferrous ion was added together with the chelating agents to the mixture at a molar ratio of 1:1. Ethylenediaminetetraacetic acid (EDTA) had no stimulatory effect on lipid peroxidation. Ferrous ion-EDTA complex increased lipid peroxidation by only 20-30%, which was lower than that obtained by addition of the same concentration of ferrous ion alone. On the other hand, manganese and calcium ions, which are also inhibitors of lipid peroxidation, had no ability to stimulate lipid peroxidation even in the presence of extra ferrous ions. Changes in the lipid peroxidation by chelating agents affected the apparent activity of ethylmorphine N-demethylation.

2,2'-Dipyridyl↗
PubMed1977

Cause of decrease of ethylmorphine N-demethylase activity of lipid peroxidation in microsomes from the rat, guinea pig and rabbit.

There were marked differences among animal species between NADPH-dependent and ascorbic acid-Fe++-dependent lipid peroxidation. In NADPH-dependent lipid peroxidation, this activity occurred to the greatest extent in rats followed by guinea pigs and rabbits and such was much lower in rabbits than in guinea pigs. On the other hand, rabbit microsomes exhibited higher lipid peroxidation activity than guinea pigs in ascorbic acid plus Fe++ or Fe++-dependent lipid peroxidation although the activity was still lower than in rats. The ascorbic acid plus Fe++-stimulated lipid peroxidation produced a decrease in ethylmorphine N-demethylase activity which was closely related to ethylmorphine-enhanced NADPH-cytochrome P-450 reductase activity but was not related to the change of the apparent content of cytochrome P-450 in all animal species. These results indicate that decrease of NADPH-cytochrome P-450 reductase activity induces a decrease in ethylmorphine N-demethylase activity by lipid peroxidation.

Animals↗
PubMed1977

Inhibition by cyanide of drug oxidations in rat liver microsomes.

Cyanide inhibited microsomal activities of aniline hydroxylation and aminopyrine, ethylmorphine and codeine demethylations and produced a modified type II difference spectrum of cytochrome P-450 to give two spectral dissociation constants, 0.21mM and 1.05 mM. The binding of cyanide to cytochrome P-450 resulted in innhibition of NADPH-cytochrome P-450 reductase activity. The cyanide inhibition of drug oxidations was partially avoided by increasing oxygen tension. A possible mechanism for the inhibition of drug oxidations by cyanide is discussed.

Aminopyrine↗
PubMed1977

Enhancement of NADPH-dependent lipid peroxidation activity by ethylene-diamineteraacetic acid (EDTA) in the presence of ferrous ion in rabbit liver microsomes.

The addition of EDTA to the incubation mixture containing rabbit liver microsomes and ferrous ion resulted in 2-fold increase of lipid peroxidation activity. Such an enhancement was not observed in rat liver microsomes. The maximum lipid peroxidation activity seen in rabbit microsomes in the presence of EDTA and ferrous ion was about 80% that seen in rat liver microsomes. From these results, it is likely that low lipid peroxidation activity in rabbit liver microsomes may account for the insufficiency of an EDTA-LIKE FACTORS(S) IN RABBIT LIVER MICROSOMES.

Animals↗
PubMed1977

Induction by carbon tetrachloride of a lipid peroxidation inhibitor (LPI) present in rat liver soluble fraction.

Oral administration of an adequate amount of carbon tetrachloride to rats resulted in an increase in the ability of the soluble fraction to inhibit microsomal NADPH-dependent lipid peroxidation. Aso, feeding of a fat-free, high carbohydrate diet to rats led an increase in the ability of the soluble fraction to prevent lipid peroxidation. Partial purification of the soluble factor inhibiting lipid peroxidation (LPI) by means of polyethylene glycol 6,000 (PEG) fractionation and hydroxylapatite column chromatography indicated that LPI is not glutathion peroxidase.

Animals↗
PubMed1976

Effect of lyophilization and storage of liver 9,000xg supernatant fraction on the metabolism of imipramine in several species of animals.

Effects of lyophilization and storage of liver 9,000xg supernatant fraction on the activity of drug metabolizing enzymes in some species of animals were studied. Imipramine metabolizing enzyme activity and the content of cytochrome P-450 were stable for, at least, one month without any loss of the activity when lyophilized liver 9,000xg supernatant fraction of some animal species, i.e., rat, mouse, guinea pig, rabbit and dog, was stored under reduced pressure in a deep freezer (-20 degrees C). There were no differences of imipramine metabolism between lyophilized liver 9,000xg supernatant fraction which was kept in a deep freezer for one month and a fresh fraction which was prepared immediately before determinations of the enzyme activity and cytochrome P-450. The data presented here indicated that the lyophilized preparation of the liver 9,000xg supernatant as well as the fresh preparation can be used for the determination of the drug metabolizing enzyme activity.

Animals↗
PubMed1975

Potent alpha-adrenoceptor action of soterenol on vascular and other smooth muscle.

Treatment with soterenol (0.3-300 mug/kg, i.v.) increased the mean arterial blood pressure and decreased heart rate in rabbits. Soterenol caused a dose-dependent contraction of rabbit aorta and portal vein, guinea-pig vas deferens and cat nicitating membrane which was inhibited by phentolamine. Other beta-agonists such as isoproterenol, salbutamol and terbutaline did not exhibit similar effects. Soterenol had potent stimulant action on the alpha-receptor of the smooth muscle.

Adrenergic alpha-Agonists↗
PubMed1975

Role of the tryptophan group in the action of pullulanase of Aerobacter aerogenes.

1. Pullulanase [EC 3.2.1.4.] was inhibited by Hg2+, N-bromosuccinimide, 2-hydroxy-5-nitrobenzyl bromide, riboflavine 5'-phosphate, histamine, imidazole, and carbodiimide. 2. The tryptophan groups of the pullulanase were modified by N-bromosuccinimede. It was found that one or two of the 25 tryptophan groups seemed to be important for the activity. 3. Studies on difference spectra using various substrates suggested that the tryptophan groups were important for the formation of an enzyme-substrate complex.

2-Hydroxy-5-nitrobenzyl Bromide↗
PubMed1975

Metabolic studies on metiazinic acid I. Absorption, distribution, excretion and metabolism in rats and rabbits.

Absorption, distribution, excretion and metabolism after oral administration of 3-H-labelled metiazinic acid were studied. The administered radioactivity was excreted through both the urinary and fecal routes. The maximum levels of concentration in blood and most tissues were shown with 3 hr after dosing. The highest radioactivity was found in the kidney throughout all experiments. Relatively high radioactivity was observed in inflammatory-treated parts in rats. Unchanged compound, metiazinic acid S-oxide and these conjugates were found in urine and feces. Approximately 60% of the unchanged form was observed in plasma after 6 hr.

Animals↗