Hiroyuki Kodama

Improvement of the anoxia-induced mitochondrial dysfunction by membrane modulation

The mitochondrial dysfunction induced by anoxia in vitro was improved with chlorpromazine, cepharanthine, bromophenacyl bromide, and mepacrine without affecting phospholipid or adenine nucleotide metabolisms. The drugs inhibited lipid peroxidation by Fe2+, mitochondrial disruption by Ca2+, and membrane perturbation by lysolecithin, and retained the activity to control H+ permeability across mitochondrial membranes. The drugs appeared to preserve the functions by acting to suppress the development of membrane deterioration which may have resided in the deenergization of mitochondria in the absence of oxygen.

Unusual metabolism of sulfur-containing amino acids in rats treated with dl-propargylglycine

S-(2-Hydroxy-2-carboxyethyl)homocysteine, S-(3-hydroxy-3-carboxy-n-propyl)-cysteine, N-acylated S-(beta-carboxyethyl)cysteine, and N-acylated S-(3-hydroxy-3-carboxy-n-propyl) cysteine were excreted in the urine after DL-propargylglycine treatment. Cystathionine was also accumulated in several tissues of DL-propargylglycine-treated rats. N-Monoacetylcystathione was found in the liver of rats and was also detected in the kidney and serum. Cystathionine gamma-lyase activity in liver decreased to about 4% of that of control rats 24 h after the DL-propargylglycine injection, and alanine aminotransferase activity decreased to about 35% of that of control rats. On the other hand, aspartate aminotransferase and cystathionine beta-synthese activity did not show significant changes from those of control rats. The ability of normal tissues to synthesize cystathionine utilizing cystathionine beta-synthase was 1.98 +/- 0.40 mumol/min/g in liver, 0.61 +/- 0.13 in kidney, and 0.18 +/- 0.015 in brain. The maximal contents of cystathionine in rat tissues and the administered amounts of DL-propargylglycine agreed well with the ability to synthesize cystathionine in each tissue.

Cystathionine Accumulation in Various Regions of Brain of DL-Propargylglycine-Treated Rats

Abstract: The contents of cystathionine and taurine, as well as cystathionine β‐synthase activity in various regions of the brains of normal and DL‐propargylglycinetreated rats, were measured. The content of cystathionine in each region of brain increased gradually from 0.5 mg to 20 mg/200 g body weight in relation to the dose of DL‐propargylglycine. Cystathionine was found to be unevenly distributed in brains of both normal and DL‐propargylglycine‐treated rats. On the other hand, the activity of cystathionine β‐synthase was evenly distributed in various regions of normal rat brain, and was unaltered following treatment of rats with DL‐propargylglycine. The concentration of taurine was similarly unaffected by DL‐propargylglycine injection.

Determination of cystathionine in rat tissues using isotachophoresis

A method for measurement of cystathionine in biological samples has been developed by using an isotachophoretic analyzer. The determination of the amount of cystathionine was carried out by measuring a zone length of cystathionine in isotachophoresis. The amount of cystathionine in brains of normal rats determined by using this method was 0.084 +/- 0.023 mumol/g. This value agreed well with earlier reports. The amount of cystathionine in rats with experimental cystathioninuria was determined in several tissues. The results determined by using this method for the determination of cystathionine in the rat tissues agreed well with the results obtained by using an amino acid analyzer.

Contents of Cystathionine and Taurine in Various Cerebellar Regions of dl‐Propargylglycine‐Treated Rats

Abstract: The contents of cystathionine and taurine, as well as cystathionine β‐synthase activity, in various cerebellar regions and pineal body of normal and dl‐propargylgly‐cine‐treated rats were measured. The contents of cystathionine and taurine were found to be distributed unevenly in cerebellar regions of brain of both normal and dl‐propargylglycine‐treated rats. The content of cystathionine in each cerebellar region and pineal body increased gradually when the dose of DL‐propargylglycine was increased from 10 mg to 30 mg per 200 g body weight. On the other hand, taurine content in each cerebellar region and pineal body decreased with the administration of 30 mg of dl‐propargylglycine per 200 g body weight. The contents of cystathionine and taurine were greater in the pineal body than in various cerebellar regions. The activity of cystathionine β‐synthase was also distributed unevenly in various cerebellar regions of normal rat brain, and was unaltered following treatment of rats with dl‐propargylglycine.

Activity of prolidase isoenzymes in the rat brain: subcellular and regional distribution during development.

Prolidase deficiency is characterized by chronic ulcerative dermatitis, mental retardation, and frequent infections. In the present study we examined the characteristics of rat brain prolidase isoenzymes. Prolidase isoenzymes (PD I and PD II) were isolated from the rat brain using DEAE cellulose column chromatography. PD I showed higher activity against seryl-proline and alanyl-proline, while PD II was particularly active against methionyl-proline. Prolidase activity in the whole brain and in the different brain regions showed higher activity against methionyl-proline and seryl-proline. PD II activity was highest in the hippocampus, followed by the cerebellum, cerebral cortex, caudatum, and the midbrain. The most rapid changes in the activities of PD I and PD II occurred perinatally, with a peak at three days before birth and a nadir at two days after birth, which then gradually increased until 21 days. N-benzyloxycarbonyl-l-proline inhibited PD I activity against various substrates in a dose-dependent manner. In contrast, there was no inhibition of PD II activity against methionyl-proline at low concentrations. In summary, these data suggest that maintenance of levels of proline, other amino acids and peptides containing proline in the rat brain is regulated by prolidase isoenzymes. The age-related alterations in PD I and PD II also may help to elucidate the fundation of prolidase isoenzymes in brain nervous system.