Abstract：
Some weakly basic compounds lead to cell death accompanied by cellular vacuolation. The novel analgesic agent, 4-dimethylamino-1-{3-(1-methyl-1H-imidazole-2-yl)propanoyl}piperidine (DMIP), is a hydrophilic and weakly basic compound that induces vacuolation in the vascular smooth muscle cells in dogs. Here, we investigated the vacuolation mechanism and the potential cytotoxicity of DMIP using human aortic vascular smooth muscle cells. When cells were treated with DMIP (0.1, 0.3, and 1 mM) for 6, 24, and 48 h, clear cytoplasmic vacuolation was observed at 1 mM after 24 and 48 h, along with an increase in the intracellular DMIP concentration. The vacuolation and intracellular DMIP were markedly reduced by bafilomycin A1, a vacuolar H+-ATPase inhibitor. The late endosome marker Rab7 and lysosome marker LAMP-2 were highly expressed but the early endosome marker Rab5 and autophagosome marker LC3 were not expressed specifically on the vacuolar membranes. These results suggested that the most vacuoles were enlarged late endosomes/lysosomes, resulting from the accumulation of DMIP by ion trapping. Moreover, DMIP did not affect lysosomal membrane integrity and was less cytotoxic than chloroquine, an inducer of phospholipidosis. The current study provides further insight into the mechanisms of vacuolation and lysosomal trapping induced by the hydrophilic and weakly basic amine DMIP.
摘要：
一些弱碱性化合物导致伴随细胞空泡化的细胞死亡。新型镇痛剂，4-二甲基氨基-1-{3-(1-甲基-1H-咪唑-2-基)丙酰基}哌啶(DMIP)，是一种亲水性和弱碱性化合物，可在狗的血管平滑肌细胞中诱导空泡化。这里,我们使用人主动脉血管平滑肌细胞研究了DMIP的空泡化机制和潜在的细胞毒性。当细胞用DMIP（0.1、0.3和1mM）处理6、24和48小时时，在24和48小时后，在1mM观察到清晰的细胞质空泡化，随着细胞内DMIP浓度的增加。液泡H-ATPase抑制剂巴弗洛霉素A1可显着降低液泡化和细胞内DMIP。晚期内体标记物Rab7和溶酶体标记物LAMP-2高表达，而早期内体标记物Rab5和自噬体标记物LC3在液泡膜上未特异性表达。这些结果表明，大多数液泡是扩大的晚期内体/溶酶体，由于离子捕获导致DMIP的积累。此外，DMIP不影响溶酶体膜完整性，细胞毒性低于氯喹，磷脂症的诱导剂。目前的研究提供了对由亲水性和弱碱性胺DMIP诱导的液泡化和溶酶体捕获的机制的进一步了解。
