Fourie A M, Meltzer S, Berman M C, Louw A I
Biochem Int. 1983 May;6(5):581-91.
The effects of cardiotoxin on the ATPase activity and Ca2+-transport of guinea pig erythrocyte and rabbit muscle sarcoplasmic reticulum (Ca2+ + Mg2+)-ATPase (E.C.3.6.1.3) were investigated. Erythrocyte (Ca2+ + Mg2+)-ATPase was inhibited by cardiotoxin in a time- and dose-dependent fashion and inhibition appears to be irreversible. Micromolar calcium prevented this inhibitory effect. Specificity for (Ca2+ + Mg2+)-ATPase inhibition by cardiotoxin was indicated since a homologous neurotoxin had no effect. Cardiotoxin did not affect (Ca2+ + Mg2+)-ATPase activity from sarcoplasmic reticulum, but Ca2+-transport was 50% inhibited. This inhibition was not due to an increased Ca2+-efflux and could be the result of an intramolecular uncoupling of ATPase activity from Ca2+-transport. Inhibition of Ca2+-transport by cardiotoxin could not be prevented by millimolar concentrations of Ca2+. It is suggested that the biological effects of cardiotoxin could be a consequence of inhibition of plasma membrane (Ca2+ + Mg2+)-ATPases.
研究了心脏毒素对豚鼠红细胞及兔肌肉肌浆网（Ca2 + + Mg2 +）-ATP酶（E.C.3.6.1.3）的ATP酶活性和Ca2 +转运的影响。心脏毒素对红细胞（Ca2 + + Mg2 +）-ATP酶有时间和剂量依赖性抑制作用，且这种抑制似乎是不可逆的。微摩尔浓度的钙可防止这种抑制作用。由于同源神经毒素无作用，表明心脏毒素对（Ca2 + + Mg2 +）-ATP酶抑制具有特异性。心脏毒素不影响肌浆网的（Ca2 + + Mg2 +）-ATP酶活性，但Ca2 +转运被抑制50%。这种抑制不是由于Ca2 +外流增加，可能是ATP酶活性与Ca2 +转运分子内解偶联的结果。毫摩尔浓度的钙不能防止心脏毒素对Ca2 +转运的抑制。提示心脏毒素的生物学效应可能是抑制质膜（Ca2 + + Mg2 +）-ATP酶的结果。
