Effects of Kc‐400 (Polychlorinated Biphenyls) on Porphyrin Metabolism

Abstract

To investigate the influence of polychlorinated biphenyls (PCB) on porphyrin metabolism, Wistar rats were orally administered KC‐400. The mean value of liver/body weight ratio in normal rats was 3.86%, with a range of 3.44% to 5.22%. Their mean blood protoporphyrin level was 23.3 μg/dl packed cell volume (p.c.v.), with a range of 11.8 to 64.4 μg/dl p.c.v., and their mean liver protoporphyrin level was 0.17 μg/gm wet weight, with a range of 0.03 to 0.40 μg/gm wet weight. A feed containing KC‐400 (140–160 ppm) was given for 2 to 20 weeks to 20 rats. The mean value of liver/body weight ratio was 5.00%, with a range of 3.80% to 6.16%. The mean erythrocyte protoporphyrin level was 47.4 μg/dl p.c.v., with a range of 19.7 to 83.2 μg/dl p.c.v., and the mean liver protoporphyrin level was 0.36 μg/gm wet weight, with a range of 0.04 to 0.67 μg/gm wet weight. The liver coproporphyrin level showed abnormalities in 2 of 20 rats fed the feed containing KC‐400, with values of 0.71 and 9.89 μg/gm wet weight, respectively. After administration of KC‐400 feed for 43 weeks, the mean value of blood coproporphyrin level rose to 32.1 μg/dl p.c.v., with a range of 11.4 to 54.6 μg/dl p.c.v. The mean erythrocyte protoporphyrin level was 74.3 μg/dl p.c.v., with a range of 49.5 to 102.1 μg/dl p.c.v. The mean liver coproporphyrin level was elevated to 5.15 μg/gm wet weight, with a range of 0.45 to 9.48 μg/gm wet weight, and the mean liver protoporphyrin level was 0.65 μg/gm wet weight, with a range of 0.43 to 9.88 μg/gm wet weight. Thus, there was an increase in both liver porphyrin and coproporphyrin following KC‐400 feeding. Liver cells in the rats with abnormal porphyrin levels exhibited a red fluorescence. From these results, we can deduce that KC‐400 may induce abnormalities in porphyrin metabolism, when it is fed orally for a long period of time. These abnormalities in porphyrin metabolism are limited to the liver only.

Analyses of δ‐Aminolevulinic Acid Dehydratase Activity and Protoporphyrin Levels in Erythrocytes among Three Different Species

“…The analysis of erythrocyte PP was performed using the method described by Honda et al (2) and the methods are shown in Fig. 3.…”

“…It is not completely understood what kinds of abnormality in porphyrin metabolism influence ALA-D activity. Previously, we have noticed a difference in protoporphyrin levels among some species when we tried to induce experimental porphyrias (2,3). To elucidate the regulation of ALA-D activity and the differences among species in heme synthetic pathway, we compared ALA-D activity and protoporphyrin (PP) levels in erythrocytes among three different species.…”

Biochemical Studies of Experimental Porphyria

“…Additionally, there are several reports of abnormal porphyrin metabolism due to PCB; we also observed that PCB induced abnormal porphyrin metabolism in rats (3). In our clinic, we pursued urinary porphyrin analysis in a patient with a history of PCB contamination and heavy alcohol intake (4).…”