Modulation of microsomal membrane associated detoxication enzymes activity by methyl isocyanate (MIC) exposure

• Published in: Bulletin of environmental contamination and toxicology 1991-11, Vol.47 (5), p.675-681
• Main Authors: MISHRA, A, DWIVEDI, P. D, VERMA, A. S, MISHRA, J, SINHA, M, DUTTA, K. K, RAY, P. K
• Format: Article
• Language: English
• Subjects: 560300 - Chemicals Metabolism & Toxicology; Aminopyrine N-Demethylase - drug effects; Aminopyrine N-Demethylase - metabolism; Aniline Hydroxylase - drug effects; Aniline Hydroxylase - metabolism; Animals; ASIA; Biological and medical sciences; BIOLOGICAL EFFECTS; CELL CONSTITUENTS; CELL MEMBRANES; Chemical and industrial products toxicology. Toxic occupational diseases; Cyanates - poisoning; DETOXIFICATION; DEVELOPING COUNTRIES; DISEASES; endoplasmic reticulum; ENZYME ACTIVITY; ENZYMES; Glutathione Transferase - drug effects; Glutathione Transferase - metabolism; HUMAN POPULATIONS; Inactivation, Metabolic - physiology; INDIA; ISOCYANATES; Lung - enzymology; Male; Medical sciences; MEMBRANES; Membranes - enzymology; MICROSOMES; Microsomes - enzymology; Microsomes - ultrastructure; MIXED-FUNCTION OXIDASES; ORGANIC COMPOUNDS; OXIDOREDUCTASES; OXYGENASES; POPULATIONS; PROTEINS; RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT; Rats; RESPIRATORY SYSTEM DISEASES; RIBOSOMES; Sulfhydryl Compounds - metabolism; Toxicology; Various organic compounds
• ISSN: 0007-4861; 1432-0800
• DOI: 10.1007/BF01701133

Consecutive dose-dependent toxicity of methyl isocyanate (MIC) was investigated in rats for alteration in phase I and phase II membrane-bound detoxication enzymes. Activities of the enzymes were determined in the lungs of animals receiving a single exposure of 355 ppm MIC, a single exposure of 1420 ppm MIC, and repeated exposures of 355 ppm MIC. The single low-dose exposure resulted in no significant changes in enzyme activity. Two low-dose exposures resulted in a marked decrease in glutathione content with a marked increase in glutathone-S-transferase activity. Further low-dose exposures and the single high-dose exposure resulted in a highly significant decrease in the activities of aniline hydroxylase, aminopyrine demethylase, glutathione, and total suphydryl content and a major increase in glutathione-S-transferase activity. Results indicate that toxic stress by MIC may be targeted to the microsomal membrane and that repeated exposure increases the magnitude of the stress.