抄録
We investigated the effect of thyroid hormone on phosphatidylinositol-specific phospholipase C activity in rat liver. Thyroidectomy increased the activity of the enzyme. Thyroid hormone (T4, 40μg) administration to thy-roidectomized-rats decreased phospholipase C activity. The inhibition inducedby thyroid hormone was of a non-competitive type. The higher concentration of Ca2+ strongly inhibited the activity of the enzyme obtained from thyroidecto-mized-rats' liver in vitro. The diminished activity of the enzyme obtained from thyroxine-treated-thyroidectomized-rats was recovered by pretreatment of the enzyme with EGTA. The activity of the enzyme derived from thyroidectomized-rats was not affected by EGTA treatment.
These results suggest that thyroid hormone decreases the activity of phos-phatidylinositol-specific phospholipase C activity through the mobilization of Ca2+ in the intracellular space.
