Eiko Shiohara

Subcellular aldehyde dehydrogenase activity and acetaldehyde oxidation by isolated intact mitochondria of rat brain and liver after acetaldehyde treatment

The effect of treatment of rats with acetaldehyde on the subcellular NAD+-aldehyde dehydrogenase (EC 1.2.1.3, ALDH) activities and acetaldehyde oxidation by isolated intact mitochondria of the liver and the brain was studied. Inhalation of acetaldehyde caused a significant decrease in the liver mitochondrial low Km-ALDH activity, while brain mitochondrial ALDH activity remained unchanged. Acetaldehyde oxidation by isolated intact liver mitochondria decreased significantly but that by brain mitochondria remained unchanged after acetaldehyde inhalation. These findings raise the possibility that the brain enzyme may be exposed to lower concentration of acetaldehyde than the liver enzyme.

Genetic control of responsiveness of rat liver supernatant aldehyde dehydrogenase to phenobarbital and 3-methylcholanthrene

The responsiveness of the hepatic supernatant NAD+-dependent aldehyde dehydrogenase with a high Km value (high Km-AldDH) to phenobarbital (PB) and 3-methylcholanthrene (3-MC) treatment was studied in male rats of three strains; Wistar, Long-Evans, and Sprague-Dawley.A remarkable strain difference in the response of the enzyme to PB or 3-MC was observed. In rats of the Wistar strain the enzyme activity remained unchanged (“non-responsive”) in all rats after treatment with PB while it increased (“responsive”) 5- to 19-fold in all rats after treatment with 3-MC. The enzyme activity increased 8- to 20-fold and 2- to 8-fold respectively after treatment with PB and 3-MC in all rats of the Long-Evans strain. In rats of the Sprague-Dawley strain the enzyme activity remained unchanged in half of all the rats treated with PB or 3-MC and increased 2- to 7-fold over the basal level in half of the treated rats. The non-responsive rats to PB were all responsive to 3-MC treatment while the responsive rats to PB were responsive in 65% and non-responsive in 35% to 3-MC treatment.

Acetaldehyde level in the blood and liver aldehyde dehydrogenase activities in trichloroethylene-treated rats.

The liver NAD+-dependent aldehyde dehydrogenase (AldDH) activity and the acetaldehyde level in the blood during ethanol metabolism after trichloroethylene (trichlene) exposure were studied in rats. Trichlene inhalation caused large elevations in acetaldehyde levels during ethanol metabolism and caused decreases in the activity of the AldDH with a low Km value in mitochondrial and soluble fractions of liver cells. No significant effects were found in the activity of the high Km-enzyme in mitochondrial, soluble and microsomal fractions. Time course of inhibition of the mitochondrial low Km-enzyme and that of elevations in acetaldehyde levels during ethanol metabolism after trichlene exposure were similar. These findings suggest that acetaldehyde formed from ethanol in vivo is oxidized primarily by the mitochondrial low Km-enzyme.

Effect of chronic administration of acetaldehyde by inhalation on (Na+ + K+)-activated adenosine triphosphatase activity of rat brain membranes

The effect of chronic acetaldehyde inhalation on (Na+ + K+)-ATPase (EC 3.6.1.3) activities of subcellular fractions of the rat cerebral cortex was studied. Chronic administration of acetaldehyde by inhalation for 4-21 weeks caused significant increases in the enzyme activities of both the synaptosomal plasma membrane (SPM) fraction and the microsomal (MC) fraction. This indicates the change in neural membrane functions of the brain after acetaldehyde treatment. Mg2+-ATPase activities of both subcellular fractions remained unchanged after acetaldehyde treatment.

ACTIVITIES OF NAD+-DEPENDENT ALDEHYDE DEHYDROGENASE AND ALCOHOL DEHYDROGENASE IN THE LIVER OF SPONTANEOUSLY HYPERTENSIVE RATS IN THE PROCESS OF DEVELOPMENT

1. The difference in the basal activities of NAD+‐dependent aldehyde dehydrogenase (ALDH) and alcohol dehydrogenase (ADH) was investigated in the liver of age‐matched spontaneously hypertensive (SH) and normotensive Wistar Kyoto (WK) rats.