To elicidate the mechanism of porphyrias, it is necessary to clarify the activities of all enzymes related to porphyrin biosynthesis. As a link in the chain of the studies, erythrocyte
δ-aminole-vulinic acid dehydrase (ALA-D) activities were measured. The mean values of the erythrocyte ALA-D activity of mice, humans and guinea pigs were 0.37, 0.77 and 2.49
μmol PBG/ml pcv/h, respectively. These activities increased in proportion to the erythrocyte protoporphyrin (PP) levels. The mean value of the human erythrocyte ALA-D activity was 0.78
μmol PBG/ml pcv/h in males, and 0.62
μmol PBG/ml pcv/h in females. There was no significant differences between the activities of both sexes, statistically. The erythrocyte ALA-D activity in griseofulvin (GF)-fed mice (GF induced protoporphyria) did not differ from that of a control group statistically. But, the erythrocyte PP levels were remarkably elevated in the GF-fed group, compared with the control. In guinea pigs, the activity of erythrocyte ALA-D showed no difference compared with a control group. However, the erythrocyte PP levels were elevated in GF-fed group of guinea pigs, compared with the control groups. Thus the ALA-D activity may represent factors related to porphyrin metabolism rather than to
δ-aminolevulinic acid synthetase. ALA-D activity cannot therefore serve as an index of porphyrin metabolism, under abnormal conditions. The mean value of ALA-D activity in 16 samples collected from 2 patients with porphyria cutanea tarda was 0.40
μmol PBG/ml pcv/h, and the activity tended to the decrease compared with a control group.
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