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Limitations on the uptake of mercury vapour by human erythrocytes in a closed exposure system
Author(s) -
Halbach Stefan
Publication year - 1981
Publication title -
journal of applied toxicology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.784
H-Index - 87
eISSN - 1099-1263
pISSN - 0260-437X
DOI - 10.1002/jat.2550010607
Subject(s) - hydrogen peroxide , chemistry , oxidizing agent , mercury (programming language) , catalase , peroxide , in vitro , limiting , biochemistry , enzyme , organic chemistry , mechanical engineering , computer science , engineering , programming language
Previous in vitro studies using the exposure of suspensions of normal human erythrocytes to mercury vapour (Hg°) in Warburg vessels revealed a broad variation of the cellular Hg uptake in the presence of hydrogen peroxide and furnished evidence for an oxidation of Hg° by the catalase‐H 2 O 2 pathway. This report describes the uptake of Hg° in the same exposure system as it depends on haematocrit, H 2 O 2 supplementation and exposure time. The results indicate that the uptake of vapour by the whole suspensions was virtually independent of haematocrit and of the H 2 O 2 supplementation at high rates of H 2 O 2 infusion, whereas at low rates it was directly proportional to the amount of peroxide added. Since the retention of mercury by the medium is negligible, the haemoglobin‐related (specific) uptake is inversely proportional to the haematocrit at high rates of H 2 O 2 infusion. These results are consistent with the conclusion that the incorporation of Hg° by erythrocytes is controlled by two processes: transfer of vapour to the cells and enzymic oxidation. The net rate of uptake is limited by the oxidizing capacity at low, and by the vapour transfer at high H 2 O 2 supplementation. As a practical consequence of these findings the spread of the specific uptakes reported in the literature is considerably reduced if the values observed when transfer becomes rate limiting are related to the haematocrit.