Sewell R B, Barham S S, LaRusso N F
Gastroenterology. 1983 Nov;85(5):1146-53.
In these experiments, we tested the hypothesis that chloroquine, a lysosomotropic agent which modifies protein and lipid metabolism by hepatocyte lysosomes, would alter the biliary excretion of lipids and lysosomal enzymes. We treated male rats for 5 days with intraperitoneal chloroquine (50 mg/kg body wt, n = 9) or saline (n = 8) and collected bile for 6 h via bile fistulas; rats were then killed and livers homogenized for biochemical analyses or processed for electron microscopy. Chloroquine markedly increased the biliary excretion of three lysosomal enzymes (mean +/- SEM) expressed as milliunits of activity per gram liver: N-acetyl-beta-glucosaminidase (24.4 +/- 2.7 vs. 12.5 +/- 1.4, p less than 0.01), beta-glucuronidase (26.4 +/- 4.7 vs. 10.9 +/- 1.4, p less than 0.01), and beta-galactosidase (9.8 +/- 1.7 vs. 5.5 +/- 0.8, p less than 0.05). In contrast, biliary outputs of enzymes associated with other organelles (e.g., alkaline phosphodiesterase I and lactic dehydrogenase) were unaffected by chloroquine treatment. Biliary cholesterol secretion was decreased after chloroquine administration (0.28 +/- 0.02 mumol/g liver vs. 0.39 +/- 0.03 mumol/g liver, p less than 0.01), but bile acid and phospholipid secretion were not altered; as a result, cholesterol saturation of bile decreased by 22% (p less than 0.05). Hepatic activities of all three lysosomal enzymes were increased after chloroquine administration (p less than 0.04); activities of enzymes associated with mitochondria, plasma membrane, endoplasmic reticulum, and cell sap were not altered. Morphometric analysis of electron micrographs of rat livers demonstrated a marked increase (p less than 0.001) in the number of lysosomelike vesicles and autophagic vacuoles in the vicinity of bile canaliculi after chloroquine administration; also, the number of canalicular microvilli decreased (p less than 0.003) after chloroquine treatment. We conclude that altered hepatic lysosomal morphology and function after chloroquine is accompanied by marked changes in outputs of lipids and lysosomal enzymes into bile. These findings call attention to a possible role for hepatic lysosomes in modulating biliary protein and lipid secretion.
在这些实验中，我们检验了以下假设：氯喹，一种通过肝细胞溶酶体改变蛋白质和脂质代谢的溶酶体亲和剂，会改变脂质和溶酶体酶的胆汁排泄。我们用腹腔注射氯喹（50毫克/千克体重，n = 9）或生理盐水（n = 8）对雄性大鼠进行了5天的处理，并通过胆管瘘收集6小时的胆汁；然后处死大鼠，将肝脏匀浆用于生化分析或进行电子显微镜检查。氯喹显著增加了三种溶酶体酶的胆汁排泄量（平均值±标准误），以每克肝脏的毫单位活性表示：N - 乙酰 - β - 葡萄糖胺酶（24.4±2.7对12.5±1.4，p < 0.01），β - 葡萄糖醛酸酶（26.4±4.7对10.9±1.4，p < 0.01），以及β - 半乳糖苷酶（9.8±1.7对5.5±0.8，p < 0.05）。相比之下，与其他细胞器相关的酶（如碱性磷酸二酯酶I和乳酸脱氢酶）的胆汁输出不受氯喹处理的影响。氯喹给药后胆汁胆固醇分泌减少（0.28±0.02微摩尔/克肝脏对0.39±0.03微摩尔/克肝脏，p < 0.01），但胆汁酸和磷脂分泌未改变；结果，胆汁的胆固醇饱和度降低了22%（p < 0.05）。氯喹给药后所有三种溶酶体酶的肝脏活性均增加（p < 0.04）；与线粒体、质膜、内质网和细胞液相关的酶活性未改变。对大鼠肝脏电子显微镜照片的形态计量分析表明，氯喹给药后胆小管附近溶酶体样小泡和自噬泡的数量显著增加（p < 0.001）；此外，氯喹处理后胆小管微绒毛的数量减少（p < 0.003）。我们得出结论，氯喹后肝脏溶酶体形态和功能的改变伴随着脂质和溶酶体酶向胆汁输出的显著变化。这些发现提请注意肝脏溶酶体在调节胆汁蛋白质和脂质分泌中可能的作用。
