Zager R A
Fred Hutchinson Cancer Research Center, Seattle, Washington, USA.
Kidney Int. 1995 May;47(5):1336-45. doi: 10.1038/ki.1995.189.
Following experimental rhabdomyolysis, animals become resistant to heme protein-induced acute renal failure (ARF). The goals of this study were to: (a) ascertain whether this resistance, previously documented only in vivo, is expressed directly at the proximal tubular cell level; (b) determine whether heme proteinuria (vs. other consequences of rhabdomyolysis) is its trigger; and (c) ascertain some of its subcellular determinants. Rats were injected with a borderline toxic dose of glycerol and 24 hours later proximal tubular segments (PTS) were isolated for study. Their vulnerability to diverse forms of injury (FeSO4-induced oxidant stress, hypoxia, Ca2+ ionophore, cytochalasin D, PLA2) was compared to that found in normal PTS. Post-glycerol PTS manifested significant resistance to each insult (decreased lactate dehydrogenase +/- N-acetyl-beta-D-glucosaminidase release). Protection against FeSO4 was virtually complete and it was associated with a 50% decrease in membrane lipid peroxidation. No decrease in hydroxyl radical generation was noted during the FeSO4 challenge (salicylate trap assessment), suggesting a primary increase in membrane resistance to attack. That PLA2 addition caused less deacylation, plasma membrane enzyme (alanine aminopeptidase) release, and LDH leakage from post-glycerol versus normal tubules supported this hypothesis. To test whether cytoresistance was specifically triggered by heme proteins (vs. being a non-specific filtered protein effect, or a result of endotoxin cascade activation), rats were injected with purified myoglobin, non-heme containing filterable proteins, or endotoxin. Only myoglobin induced cytoresistance. In vivo heme oxygenase inhibition (tin-protoporphyrin) did not block the emergence of cytoresistance and it was expressed despite Na,K-ATPase inhibition (ouabain) or cytoskeletal disruption (cytochalasin D). In vivo heat shock failed to protect. In conclusion, (1) rhabdomyolysis induces broad based proximal tubular cytoresistance; (2) heme proteinuria is its trigger; and (3) it is most easily explained by a primary increase in plasma membrane resistance to attack.
实验性横纹肌溶解后，动物对血红素蛋白诱导的急性肾衰竭（ARF）产生抗性。本研究的目的是：（a）确定这种先前仅在体内记录的抗性是否在近端肾小管细胞水平直接表现出来；（b）确定血红素蛋白尿（相对于横纹肌溶解的其他后果）是否为其触发因素；（c）确定其一些亚细胞决定因素。给大鼠注射临界毒性剂量的甘油，24小时后分离近端肾小管节段（PTS）进行研究。将它们对多种损伤形式（硫酸亚铁诱导的氧化应激、缺氧、钙离子载体、细胞松弛素D、磷脂酶A2）的易感性与正常PTS中的情况进行比较。甘油处理后的PTS对每种损伤均表现出显著抗性（乳酸脱氢酶+/- N-乙酰-β-D-氨基葡萄糖苷酶释放减少）。对硫酸亚铁的保护几乎是完全的，并且与膜脂质过氧化减少50%相关。在硫酸亚铁攻击期间（水杨酸盐捕获评估）未观察到羟基自由基生成减少，这表明膜对攻击的抗性主要增加。与正常肾小管相比，添加磷脂酶A2后，甘油处理后的肾小管脱酰作用、质膜酶（丙氨酸氨肽酶）释放和乳酸脱氢酶泄漏较少，支持了这一假设。为了测试细胞抗性是否由血红素蛋白特异性触发（相对于非特异性滤过蛋白效应或内毒素级联激活的结果），给大鼠注射纯化的肌红蛋白、不含血红素的可滤过蛋白或内毒素。只有肌红蛋白诱导细胞抗性。体内血红素加氧酶抑制（锡原卟啉）并未阻止细胞抗性的出现，并且尽管存在钠钾ATP酶抑制（哇巴因）或细胞骨架破坏（细胞松弛素D），细胞抗性仍表现出来。体内热休克未能起到保护作用。总之，（1）横纹肌溶解诱导广泛的近端肾小管细胞抗性；（2）血红素蛋白尿是其触发因素；（3）最容易用质膜对攻击的抗性主要增加来解释。
