Toxicity of polycyclic aromatic hydrocarbons. II. Effect of NO2-nitrated phenanthrene and pyrene on blood chemistry in rats.

Male Sprague-Dawley rats were treated with a single ip injection of dimethyl sulfoxide (DMSO), phenanthrene, nitrated products of phenanthrene, pyrene, or nitrated products of pyrene. Phenanthrene, pyrene and their nitrated products were dissolved in DMSO. Phenanthrene produced a significant elevation of serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels relative to DMSO-injected rats 24 hr after injection. Gamma-glutamyl transpeptidase (GGTP) levels were significantly increased for groups treated with phenanthrene when compared with the DMSO group 72 hr after injection. Nitrated products of phenanthrene produced a significant elevation of serum AST, ALT, sorbitol dehydrogenase (SDH), and GGTP levels when compared with groups treated with DMSO and phenanthrene 24 hr after injection. Four of six rats in the nitrated phenanthrene treatment group died between 48 and 72 hr after the injection. Injection of pyrene caused no significant increases in serum enzyme activities. Significant changes in the serum AST, SDH and LDH levels were observed with the nitrated products of pyrene at 24 hr. Only SDH levels were significantly different when pyrene and its nitrated products were compared. No significant differences were detected at 72 hr with the nitrated products of pyrene. As supported by serum chemistry, this study suggests that the products of the reaction of NO2 with two model polynuclear aromatic hydrocarbons (PAH) are hepatotoxic. Both pyrene and phenanthrene form nitrated products that are more toxic than the parent PAH, but the nitrated products of phenanthrene appear to be more toxic than the nitration products of pyrene.