Hightower K R, Hind D
Curr Eye Res. 1982;2(4):239-46. doi: 10.3109/02713688209011625.
Experiments were designed to investigate the effects of lens calcium on the Na/K pump since elevated calcium and sodium often accompanies lens opacification. An increase in lens calcium was accomplished by culturing lenses in calcium-rich media at 21 degrees C in the absence of poisons which might directly alter sodium transport. Calcium loaded lenses were subsequently incubated at 37 degrees C in a normal culture medium to assess membrane transport function. A five-fold increase in total lens calcium to 1.45mM, resulting in a 4% increase in membrane bound calcium, had little effect on the cation pump. However, an increase in lens calcium by a factor of 100 caused a 4-fold increase in membrane bound calcium, a 50% decrease in (Na/K)-ATPase activity, and a 40% decrease in 86Rb uptake after an incubation period of 20 hrs. Details of the mechanism of enzyme inhibition remain obscure, but the data suggest the inhibition is predominantly irreversible and does not involve an interaction between calcium and ATP.
由于晶状体浑浊常常伴随着钙和钠含量的升高，因此设计了实验来研究晶状体钙对钠钾泵的影响。通过在21摄氏度下于富含钙的培养基中培养晶状体来实现晶状体钙含量的增加，培养过程中不存在可能直接改变钠转运的毒物。随后将加载了钙的晶状体在37摄氏度下于正常培养基中孵育，以评估膜转运功能。晶状体总钙含量增加至1.45mM，增长了五倍，导致膜结合钙增加了4%，但对阳离子泵几乎没有影响。然而，晶状体钙含量增加100倍会导致膜结合钙增加4倍，(Na/K)-ATP酶活性降低50%，并且在孵育20小时后86Rb摄取量降低40%。酶抑制机制的细节仍然不清楚，但数据表明这种抑制主要是不可逆的，并且不涉及钙与ATP之间的相互作用。
