結合型ビタミンB_1の動的平衡について : (II)肝障害時のビタミンB_1代謝障害とフォスファターゼの関係

概要

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It is not asserted from the view of transition of bound thiamine to total thiamine ratio that the activity of phosphorylation of thiamine is always impeded in liver damage. On the other hand, phosphatase activity is strongly increased in damaged liver. Therefore, assuming that the liver phosphatase and the dephosphorylating enzyme of bound thiamine be identical, there is a possibility of explanation that the decrease of thiamine content in liver and the increase of thiamine excretion into urine at liver damage are due to that the amount of outflow of free thiamine from liver is increased, not by decrease of activity of phosphorylation but rather by acceleration of phosphatase activity. Furthermore, we investigated the influence of thiamine on phosphatase activity, and found that free thiamine accelerates the activity of normal liver phosphatase and, on the other hand, impedes the activity of damaged liver phosphatase. This fact was observed both in vitro and in vivo. and is thought to be enough to explain the mechanism of so-called "flooding-effect" of thiamine. Phosphatase in kidney is not influenced much by thiamine.
日本ビタミン学会の論文