Jernigan H M, Laranang A S
Curr Eye Res. 1984 Jan;3(1):121-6. doi: 10.3109/02713688408997193.
Previous studies have indicated that photosensitized oxidation of cultured rat lenses greatly decreases their ability to accumulate labeled choline from the medium. This effect required a photosensitizer, light, and oxygen. Choline accumulation appeared to be somewhat more sensitive to damage than 86Rb accumulation. The following studies were designed to test the relative sensitivity of choline metabolism to photo-oxidation and to determine whether the primary site of damage involved the choline carrier or the choline phosphorylation mechanism (which traps choline in the lens). The ATP concentration and the rates of 3H-choline transport, choline phosphorylation, and 86Rb transport were measured in individual rat lenses. These parameters were compared in lenses cultured for 1-16 hr with or without 50 microM riboflavin. In the lenses exposed to riboflavin and light, choline uptake decreased to less than 40% of control within 4 hr, while 86Rb uptake decreased more slowly, approaching 40% of control at 12 hr. The difference in damage between the two transport systems was especially evident at 4-8 hr. Subsequent to the effect on choline transport, photo-oxidation also caused a progressive and concurrent decrease in both ATP concentration and choline phosphorylation. The time course of the observed changes demonstrated that the early decrease in accumulation of 3H-choline in these lenses resulted from effects on transport rather than from decreased conversion to phosphorylcholine.
先前的研究表明，培养的大鼠晶状体的光敏氧化作用极大地降低了它们从培养基中积累标记胆碱的能力。这种效应需要一种光敏剂、光和氧气。胆碱积累似乎比86Rb积累对损伤更为敏感。以下研究旨在测试胆碱代谢对光氧化的相对敏感性，并确定损伤的主要部位是涉及胆碱载体还是胆碱磷酸化机制（该机制将胆碱捕获在晶状体中）。在单个大鼠晶状体中测量了ATP浓度以及3H-胆碱转运、胆碱磷酸化和86Rb转运的速率。将在有或没有50微摩尔核黄素的情况下培养1至16小时的晶状体中的这些参数进行了比较。在暴露于核黄素和光的晶状体中，胆碱摄取在4小时内降至对照的40%以下，而86Rb摄取下降得更慢，在12小时时接近对照的40%。两种转运系统之间的损伤差异在4至8小时时尤为明显。在对胆碱转运产生影响之后，光氧化还导致ATP浓度和胆碱磷酸化同时进行性下降。观察到的变化的时间进程表明，这些晶状体中3H-胆碱积累的早期下降是由转运受到影响所致，而非转化为磷酸胆碱的减少所致。
