Haigler H T, McKanna J A, Cohen S
J Cell Biol. 1979 Oct;83(1):82-90. doi: 10.1083/jcb.83.1.82.
Horseradish peroxidase (HRP) uptake was used to measure fluid-phase pinocytosis in monolayers of human epithelioid carcinoma cells (A-431). Histochemistry confirmed that cell-associated HRP was restricted to intracellular vesicles. Biochemical methods showed that HRP uptake in control cultures was directly proportional to the duration of exposure. The addition of low concentrations of epidermal growth factor (EGF) to the incubation media produced a 10-fold increase in the initial rate of pinocytosis. The EGF effect was rapid (within 30 s) but transient; the rate of pinocytosis returned to control levels within 15 min. Metabolic inhibitors reduced the EGF-stimulated rate of pinocytosis by greater than 90%. A conjugate of EGF and ferritin (F:EGF) was used to simultaneously compare the intracellular locations of EGF and HRP. Much of F:EGF was internalized in approximately 100-nm vesicles, while most of the HRP was located in much larger vesicles (range 0.1--1.2 micrometer) which also contained F:EGF. The tumor-promoter 12-0-tetradecanoyl-phorbol-13-acetate, which shares several biological activities with EGF, was also effective in stimulating an increase in the rate of pinocytosis.
用辣根过氧化物酶（HRP）摄取法测定人上皮样癌细胞（A-431）单层细胞中的液相胞饮作用。组织化学证实，与细胞相关的HRP局限于细胞内小泡。生化方法表明，对照培养物中HRP的摄取与暴露持续时间成正比。向孵育培养基中添加低浓度的表皮生长因子（EGF）可使胞饮作用的初始速率增加10倍。EGF的作用迅速（30秒内）但短暂；胞饮作用速率在15分钟内恢复到对照水平。代谢抑制剂使EGF刺激的胞饮作用速率降低了90%以上。用EGF与铁蛋白的偶联物（F:EGF）同时比较EGF和HRP在细胞内的定位。大部分F:EGF被内化到约100纳米的小泡中，而大部分HRP位于大得多的小泡中（范围为0.1-1.2微米），这些小泡中也含有F:EGF。与EGF具有多种生物学活性相同的肿瘤促进剂12-0-十四烷酰佛波醇-13-乙酸酯也能有效刺激胞饮作用速率增加。
