脳虚血急性期におけるアルカリ化剤の治療効果についての実験的検討

Experimental Studies on the Therapeutic Effects of Alkalizing Agents on Acute Focal Cerebral Ischemia

　局所脳虚血急性期に対するアルカリ化剤の効果を，ネコ中大脳動脈閉塞モデルを用いて検討した。生食を投与したコントロール群では動脈血pHは徐々に低下したのに対し，0.3mol tris（hydroxymethyl）aminomethane（THAM）投与群，7％NaHCO₃投与群では動脈血pHは生理的範囲内に維持された。虚血作成6時間後，虚血中心部にあたるectosylvian, suprasylvian gyrusの脳皮質水分量は，3群間で有意差は認められなかったが，虚血辺縁部のmarginal gyrusでは，THAM投与群で他2群に比し有意に水分量の増加が抑制された。6時間後の梗塞巣はTHAM投与群ではコントロール群に比し有意に縮小した。³¹P-MRSにより測定した虚血脳組織pHの検討では，各群とも高度なアシドーシスを示し，THAM投与群では改善傾向を示すものの有意差ではなかった。

Metabolic acidosis in cerebral ischemia is consid-ered deleterious to cell function and neurological outcome. Amelioration of systemic and focal cere-bral acidosis by an alkalizing agent may reduce ischemic brain damage. The effects of 0. 3mol tris (hydroxymethyl) aminomethane (THAM) and 7% NaHCO₃ on focal cerebral ischemia produced by occlusion of the middle cerebral artery (MCA) in cats were examined. In thirty six adult cats, adjust-ment was made so that Pa0₂ and PaCO₂ would be maintained within the normal range with mechani-cal ventilation and oxygen inhalation.Focal cere-bral ischemia was produced by coagulation of the left MCA using the transorbital approach. The animals were divided into 3 groups as follows. 1) The control group received continuous intravenous administration of physiological saline (2m1/kg/ hour). 2) The THAM group received continuous intravenous administration of O.3mol THAM (2m1/kg/hour). 3) The NaHCO₃ group received continuous intravenous administration of 7% NaHCO₃ (0.7m//kg/hour) +physiological saline (1.3m//kg/hour).