[Sex difference in free erythrocyte protoporphyrin (FEP) level. II. Sex difference in FEP level in rats exposed to lead]

Abstract

An experimental study on Donryu rats was primarily carried out to elucidate sex difference in FEP level. Each of 33 male and 33 female rats was divided into 3 groups; that is, control group (5% glucose solution only), low lead dose group (Pb 0.5 mg/kg.BW) and high lead dose group (Pb 5 mg/kg.BW). Lead was injected intraperitoneally once a week for 6 wk. FEP, Ht, urinary coproporphyrin (CP-U), delta-aminolevulinic acid (ALA-U) and porphobilinogen (PBG-U) were determined once every two weeks for 6 wk, and whole blood lead (Pb-B) at the end of the experiment. Mean value of Ht was lower in females than in males throughout the period of the experiment in almost all groups. Pb-B level of all groups and erythrocyte Pb level of high dose group were higher in males than in females. FEP level without lead injection and with low lead exposure was higher in males than in females. By analysis of variance for gain from initial FEP level, only the low lead dose group demonstrated a significant sex difference (p less than 0.01); the female group tended to increase, while the male group maintained a constant level. Furthermore, FEP/Pb-B ratio in females was higher than in males only for the high dose group. The changes in ALA-U in male and female rats were comparable to those in FEP. Unlike FEP and ALA-U, CP-U level was higher in males than in females only for the high lead dose group. In this study using rats, sex difference in FEP level was different from that in human.(ABSTRACT TRUNCATED AT 250 WORDS)