竹红菌乙素对人红细胞Na^+-K^+ATPase和钠通透性光敏损伤的研究

HYPOCRELLIN B-SENSITIZED PHOTODAMAGE ON Na^+ -K^+ATPase AND SODIUM PERMEABILITY OF HUMAN ERYTHROCYTES

本文用NMR和生化方法研究了竹红菌乙素对人红细胞膜Na^+-K^+ATPase和钠通透性的光敏损伤。结果表明:在通常情况下,可同时观察到乙素对Na^+-K^+ATPase和钠通透性的光敏损伤。比较乙素、甲素、原卟啉和胆红素对上述两项指标的光敏能力,发现乙素对Na^+-K^+ATPase损伤能力与甲素和原卟啉相当,比胆红素大,对钠通透性的损伤大于其它几种敏化剂。实验指出,Na^+-K^+ATPase活力下降比钠通透性增加敏感。在乙素光敏作用时,加入Vit E可基术上保持胞内钠离子浓度不变,但无法使Na^+-K^+ATPase活力不损伤,这表明膜磷脂的结构完整对保持胞内钠浓度比较重要。对照试验指出乙素可使Na^+-K^+ATPase暗失活,这可能是经乙素介导的,由膜还原物质向氧的电子传递生成活性氧自由基攻击靶分子所致。

The hypocrellin B (HB)-sensitized photodamage on Na^+-K^+ ATPase and sodium permeability of human erythrocytes by means of NMR and biochemical techniques was studied in this paper. The decrease of the enzyme activity and increase of intracellular sodium concentration were usually observed simultaneously (Fig. 1, Fig. 2). The evidences suggested that the intcgrality of membrane phospholipid played an important role in maintaining the physiological sodium content of erythrocytes. The loss of the enzyme activity was a sensitive index compared with the increase of intracellular Na^+ concentration during the photosensitization. From the comparison tests among HB, HA, protoporphyrin and bilirubin, we found that HB had more ability to increasing intracellular Na^+ concentration than the other photosensitizations even though the photodamage on the enzyme activity caused by HB, HA, and protoporphyrin were nearly the same (Table 2). Besides the photoinactivation of Na^+-K^+ ATPase induced by HB and light, the enzyme was also inactivited in the medium containing HB in absence of light (Fig. 5). The active oxygen radicals generated though HB mediated redox-cycling might be involved in the dark inactivation of the enzyme.