CORRELATION BETWEEN VARIOUS RATIOS OF SERUM THYROID-HORMONES AND LIVER CYTOCHROME-P-450 IN CCL4-TREATED AND UNTREATED RATS

In a search for clinically useful indices of liver microsomal function , the correlation between various ratios of serum thyroid hormones, tr iiodothyronine (T-3) and reverse T-3 (rT(3)), and liver microsomal P-4 50 was investigated in CCl4-treated and untreated rats. Serum and live r samples were obtained before (untreated group, n = 15) and 4 hr afte r CCl4 administrations (0.2 ml/kg, s.c.). The CCl4-treated group (n = 11) included five randomly chosen untreated rats. In both groups, the ratios of T-3/rT(3), rT(3)/T-3, and T-3/T-3 +rT(3) correlated signific antly with liver cytochrome P-450 levels. From these results, it is su ggested that the ratios of T-3/T-3 + rT(3), T-3/rT(3), and rT(3)/T-3 c an be used as the indices of liver microsomal P-450 levels and that th yroid hormone metabolism is related to liver cytochrome P-450, as was evidenced in untreated animals.