Behavior of acetaldehyde transported in blood

Effects of vinyl acetate and acetaldehyde on sperm morphology and meiotic micronuclei in mice

The testicular genotoxic effects of vinylacetate (VA) and its hydrolysis product, acetaldehyde (AA), were studied in mice by analyzing the induction of morphologically abnormal sperm and meiotic micronuclei. VA significantly increased the frequency of sperm abnormalities at 500 mg/kg/day while lower doses were ineffective. AA did not induce abnormal sperm. Neither of the compounds influenced the frequency of meiotic micronuclei. VA, but not AA, caused a dose-dependent decrease in sperm production and a reduction of testicular weight at 500 and 125 mg/kg/day.

Blood and brain n-pentanol in inhalation exposure

Male Wistar rats exposed to 100, 300 or 600 p.p.m. n-pentanol vapour for 7 to 14 weeks during five days weekly and 6 hrs daily showed a dose-dependent blood n-pentanol concentration. The brain n-pentanol content was linearly related to the blood pentanol concentrations although this relationship changed after 14 weeks because the brain n-pentanol was significantly smaller than the respective values at 7 weeks. Valeraldehyde, the primary metabolite of n-pentanol, was only found in the brain at the highest vapour dose level. The liver n-pentanol dehydrogenase and 7-ethoxycoumarin O-deethylase activities remained unchanged while kidney ethoxycoumarin deethylase activity was enhanced in a dose-dependent manner at both time points. Brain and muscle acetylcholinesterase activities were increased by the exposure dose-dependently after 7 weeks although this effect ameliorated after 14 weeks. Moderate n-pentanol vapour exposure seems to cause metabolic and functional adaptation in its target organs.

Elimination of artifactual acetaldehyde in the measurement of human blood acetaldehyde by the use of polyethylene glycol and sodium azide: normal blood acetaldehyde levels in the dog and human after ethanol

A new procedure is described for the preparation of human blood samples for analysis of acetaldehyde and ethanol by head space gas chromatography. High concentrations of polyethylene glycol were used to remove the hemoglobin and approximately 50% of the plasma protein. Artifactual formation of acetaldehyde from ethanol was inhibited by sodium azide. Using this method, no artifactual acetaldehyde was detectable in human, dog, sheep, and rat blood when spiked with ethanol in final concentrations of 65 mM. The recovery of added acetaldehyde was approximately 80% for human dog, and sheep blood, whereas it was only 30% for rat blood. Following ethanol administration, acetaldehyde levels were determined in blood taken from the pulmonary artery and descending aorta of the dog and human, and also from the hepatic vein of the latter. The relative blood acetaldehyde concentrations at these sites were hepatic vein greater than pulmonary artery greater than descending aorta.

Aldehyde dehydrogenase in blood: a sensitive assay and inhibition by disulfiram

The characteristics of human blood aldehyde dehydrogenase with indole-3-acetaldehyde as the substrate were investigated. Blood volumes of less than 25 microliter could be assayed. The Km-value was below 10 microM for indole-3-acetaldehyde and 100 microM for NAD+. The ALDH-activity appeared to be located exclusively in the intracellular fraction of the erythrocytes. Acetaldehyde or ethanol at concentrations up to 1 and 40 mM respectively did not affect the activity. Disulfiram caused a pronounced inhibition of the enzyme both in vitro and in vivo. The blood ALDH-activity in disulfiram-treated patients was not fully restored until 6 weeks after discontinuation of the treatment. The inhibition observed in vitro was reversed completely by 2-mercaptoethanol but only partially by glutathione. No restoration of activity in blood from disulfiram-treated patients was obtained with these two reagents. The inhibition found in vitro and in vivo was more pronounced when the assays were performed with indole-3-acetaldehyde than with acetaldehyde. The results suggest that different isozymes of ALDH are involved in the assay with these two substrates.