塞栓による実験的ラット脳主幹動脈閉塞—急性期の組織pHとエネルギー代謝

TISSUE PH AND ENERGY METABOLISM IN CEREBRAL EMBOLIZATION MODEL OF RAT

　ラットの脳主幹動脈をシリコン円柱で閉塞する局所脳虚血を作成し，急性期の組織pH, ATP，NADHの変化をbiolurninescence methodを用いて定性的に評価した。閉塞側脳のcortex, caudateputamenではacidosisを示し，ATPはその一部で低下していた。Thalamus, hypothalamus, hippocampusなどの脳深部では多くは同一脳でacidosisとalkalosisを示す部位が混在し，ATPは軽度から高度に至るまでの減少を示すことが多かった。NADHはacidosisを示した部位の一部で増加したのに対し，alkalosisを示していた部位ではNADHは低下していた。これらのことから，このモデルは脳深部に強いエネルギー代謝障害を示すこと，また，組織pHの変化は種々の段階のエネルギー代謝障害を示すことが特徴であり，臨床における脳塞栓の病態の解明に有用であると考えられた。

Changes in brain tissue pH, ATP and NADH contents in the cerebral embolization model of Wistar rat were investigated by bioluminescence method. Under light anesthesia, main trunk ofcerebral artery was embolized with a silicone cylin-der (500 μm in diameter and 1 mm in length) thro-ugh the cervical internal carotid artery. Rat brain was frozen in situ at 1 or 3 hours after emboliza-tion. In some rats Evans blue was injected into the peritoneal cavity 30 minutes before freezing. Caudate putamen and cortex were often acidotic but thalamus, hypothalamus, and hippocampus were composed of both acidotic and alkalotic area. Ex-udation of Evans blue was frequently detected in the alkalotic area. ATP was decreased partially in the acidotic area. In the alkalotic area ATP was decreased to mild to severe degree.

Decreased ATP region in the acidotic area show-ed increased NADH content, whereas in the alka-lotic area NADH was diffusely decreased. From these results, alkalosis may be induced by cerebral edema due to plasma exudation. The decrease of ATP and increase of NADH in the acidotic area may demonstrate the disturbance of oxidative pho-sphorylation under anaerobic glycolysis, and the decrease of ATP and decrease of NADH in the alkalotic area may demonstrate impairment of glycolysis mainly due to brain edema.