Comparison of photosensitized plasma membrane damage caused by singlet oxygen and free radicals
Comparison of photosensitized plasma membrane damage caused by singlet oxygen and free radicals
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DOI：
10.1016/0005-2736(95)00297-9
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发表时间：
1996-04-26
影响因子：
3.4
通讯作者：
Tedesco, AC
中科院分区：
文献类型：
--
作者：
Kochevar, IE;Lambert, CR;Tedesco, AC
光敏剂形成的初始反应物质的性质对光敏性损伤膜功能的效率和选择性有很大影响。为了测试这种可能性，使用了一种光敏剂，玫瑰红（RE），它驻留在质膜上，在可见光激发下产生单线态分子氧（O-1(2)）和自由基加上O-1(2)。用紫外线辐射激发。用这种方法，0 -1(2)。自由基在质膜的相同位置形成。评估了三种质膜功能的响应，即脯氨酸运输、膜电位和膜对带电染料分子的不渗透性。比较了两个波长下稀土吸收的每光子在有氧和无氧条件下的响应效率；355 nm（紫外激发）和532 nm（可见激发）。通过测量RE三倍体的寿命来评估辐照前的除氧效率。在氧存在下，这三种膜功能在355 nm处比在532 nm处更有效地被抑制，这表明自由基比O-1更有效地启动膜组分的损伤(2)。在氧气存在下，两个波长的光敏效应的比例对于两个膜功能是相同的，但对于第三个膜功能则不是，这表明O-1(2)。自由基启动了一个共同的机制途径来破坏一些膜功能，而不是其他膜功能。除氧使355 nm诱导的光敏化效率降低了1.4 ~ 7倍。三种膜功能对O-1的敏感性(2)。-初始伤害变化超过50倍，而激进初始伤害仅变化15倍。综上所述，这些结果表明自由基和O-1(2)。在质膜的相同位置形成的膜损伤的效率和特异性各不相同，但在某些情况下，在氧气存在的情况下，可能通过共同的二次损伤机制起作用。
The efficiency and selectivity of photosensitized damage to membrane functions may be influenced strongly by the identity of the initial reactive species formed by the photosensitizer. To test this possibility, a phorosensitizer, rose bengal (RE), was used that resides in the plasma membrane and which generates singlet molecular oxygen (O-1(2).) upon excitation with visible light, and radicals plus O-1(2). upon excitation with UV radiation. With this approach, O-1(2). and radicals are formed at the same locations in the plasma membrane. The response of three plasma membrane functions, namely, proline transport, membrane potential, and membrane impermeability to charged dye molecules, was assessed. The efficiencies of the responses in the presence and absence of oxygen were compared per photon absorbed by RE at two wavelengths; 355 nm (UV excitation) and 532 nm (visible excitation). The efficiency of oxygen removal before irradiation was assessed by measuring the RE tripler lifetime. The three membrane functions were inhibited more efficiently at 355 nm than at 532 nm in the presence of oxygen indicating that the radicals are more effective at initiating damage to membrane components than O-1(2). The ratio of photosensitized effects at the two wavelengths in the presence of oxygen was the same for two membrane functions but not for the third suggesting that O-1(2). and radicals initiate a common mechanistic pathway for damage to some membrane functions but not to others. Removing oxygen reduced the efficiency of 355 nm-induced photosensitization by factors of 1.4 to 7. The sensitivity of the three membrane functions to O-1(2).-initiated damage varied over a factor of 50 whereas radical initiated damage only varied by a factor of 15. In summary, these results indicate that radicals and O-1(2). formed at the same locations in the plasma membrane vary in their efficiency and specificity for membrane damage but may, in some cases, operate by a common secondary damage mechanism in the presence of oxygen.