Okabe E, Hiyama E, Oyama M, Odajima C, Ito H, Cho Y W
Pharmacology. 1982;25(3):138-48. doi: 10.1159/000137735.
In vitro generation of free radicals by xanthine oxidase acting on hypoxanthine as a substrate induced a decreased calcium uptake velocity and reduced calcium-dependent ATPase activity of isolated sarcoplasmic reticulum (SR) vesicles from canine masseter muscle at pH 7.0. At pH 5.5 calcium uptake velocity was also reduced but ATPase activity was unaffected. Application of arachidonic acid or prostaglandin G2 induced the depression of both calcium uptake velocity and ATPase activity. The effect of arachidonic acid and prostaglandin G2 on ATPase activity depended on the pH. At pH 7.0, ATPase activity was decreased, but at pH 5.5 it was unchanged. These effects were reversed by superoxide dismutase (SOD) at pH 7.0, and by SOD plus mannitol at pH 5.5. Prostaglandin H2, prostaglandin E2 and 11,14,17-eicosatrienoic acid had no effect on calcium uptake velocity and ATPase activity at both pH 7.0 and pH 5.5. These results suggest that damage to the masseter muscle is caused by a free radical superoxide anion generated as a result of increased prostaglandins synthesis, and by the production of more lethal hydroxyl radical switched from the production of superoxide anion at low pH.
在pH 7.0条件下，黄嘌呤氧化酶以次黄嘌呤为底物在体外产生自由基，导致犬咬肌分离的肌浆网（SR）囊泡的钙摄取速度降低，钙依赖性ATP酶活性降低。在pH 5.5时，钙摄取速度也降低，但ATP酶活性未受影响。花生四烯酸或前列腺素G2的应用导致钙摄取速度和ATP酶活性均降低。花生四烯酸和前列腺素G2对ATP酶活性的影响取决于pH值。在pH 7.0时，ATP酶活性降低，但在pH 5.5时不变。在pH 7.0时，超氧化物歧化酶（SOD）可逆转这些作用，在pH 5.5时，SOD加甘露醇可逆转这些作用。前列腺素H2、前列腺素E2和11,14,17-二十碳三烯酸在pH 7.0和pH 5.5时对钙摄取速度和ATP酶活性均无影响。这些结果表明，咬肌损伤是由前列腺素合成增加产生的自由基超氧阴离子以及在低pH值下从超氧阴离子产生转变而来的更具致死性的羟基自由基引起的。
