The acute influences of arsenic compounds on the metabolism of porphyrins and heme in various organs of rats after oral or intratracheal administration of disodium arsenate (Na,HAsO,) and gallium arsenide (GaAs) were examined and compared.For the oral administration experiments, 21 or 84 mg of Na,HAsO,, or 2 or 4 g of GaAs, per cm3 saline per kg body weight of each animal was administered to Jcl: Wistar male rats and the organs were removed after exsanguination from the vein of the right axilla under anesthesia with ether, 16h after administration. In the case of intratracheal administration, rats given 8.2 or 16.4mg of Na,HAsO,, or 0.2 or 0.4g GaAs per cm3 saline per kg body weight were examined under the same experimental conditions as for the administration route.Increase in the body weight of rats was suppressed after intratracheal administration of the two arsenic compounds. In these rats the hematocrit value increased significantly. These changes were not shown by the orally administered rats. Elevation in 6-aminolevulinate synthase (ALA-S, EC 2.3.1.37) activity in erythroblasts by Na,HAs04 was much higher after intratracheal administration than after oral administration. Suppression in the activities of 6-aminolevulinate dehydratase (ALA-D, EC 4.2.1.24) and porphobilinogen deaminase (PBG-D, EC 4.3.1.8) in peripheral erythrocytes by NazHAsO, and GaAs were stronger by intratracheal administration than by the oral route. Influences of GaAs on the activity of PBG-D in rat liver were shown to be more effective by oral administration than by the intratracheal route. Oral administration of Na,HAsO, $ Author to whom all correspondence should be sent, at The Institute of Public Health, 4-6-1 Shirokanedai, Minato-ku, Tokyo, 108 Japan. It seems from these results that the different extents of the influence of arsenic compounds might depend on the routes of intake.

No abstract

No abstract

The effect of short-term inhalation of ozone (O3) on the content and metabolism of phospholipids, particularly lecithin (PC), in rat lung was studied. The PC level increased slightly, but significantly, in the lung of rats exposed to 2 ppm O3 for 3 h. However, the PC level remained within the control level following the exposure to 2.5 and 5 ppm of O3 for 3 h, while the lysolecithin (LysoPC) content greatly increased. The incorporation of [32P]orthophosphate (32Pi) and [14C]palmitic acid into PC in the lung slices obtained from the animals tended to increase following the exposure to 2 ppm for 3 h, but decreased following the exposure to O3 above 2.5 ppm for 3 h. On the other hand, the radioactivity of 32Pi in LysoPC of lung from the rats exposed to O3 above 2.5 ppm was significantly greater than that from the control. Such changes in the content of PC or LysoPC and in the incorporation of labeled precursors into them may be explained, at least in part, by the combination of the presently and previously observed changes in the activities of enzymes participating in PC metabolism pathway as follows: (1) the significant stimulation in the activity of LysoPC acyltransferase (LysoPC ATF), which can transfer fatty acids onto LysoPC, for palmitic acid at an earlier stage of the exposure to O3 at 2 and 2.5 ppm; (2) the depression in the activities of this enzyme and another ATF-LysoPC-LysoPC ATF, which can synthesize one molecule of disaturated PC from two moles of saturated-LysoPC-by increasing the O3 exposure time; and (3) the stimulation in the phospholipase A2 activity in the lung of rats exposed to 2 ppm of O3 for 6 h.

Sodium arsenate (Na2HASO4· 7H2O, As(V)) was administered to three genetically different strains of mice, ICR, C57BL/6J and DBA/2J, in a single oral dose of 54 mg kg−1 body weight. The effects on the activities of heme biosynthetic enzymes in the spleen, liver, kidney and peripheral blood were investigated. The activities of δ‐aminolevulinate synthase (ALAS, EC 2.3.1.37), catalyzing the first reaction in the heme biosynthetic pathway and the rate‐limiting enzyme for heme synthesis, δ‐aminolevuilinate dehydratase (ALAD, EC 4.2.1.24) and porphobilinogen de‐­aminase (PBGD, EC 4.3.1.8) in the spleens of the ICR strain, were remarkably reduced to 51%, 32% and 42%, respectively, in comparison with each mean value of the control group. In contrast, these activities were significantly increased in the livers of the C57BL/6J strain, and a similar trend was observed in the DBA/2J strain. In the kidneys, the ALAD activity was significantly reduced in the ICR strain, but no significant differences in the other two strains were found. These results suggest that the influence of As(V) on the activity of heme biosynthetic enzymes is most potently manifested in the spleen tissue of the ICR strain. Copyright­© 1999 John Wiley & Sons, Ltd.