The pinocytosis of 125I-labelled poly(vinylpyrrolidone), [14C]sucrose and colloidal [198Au]gold by rat yolk sac cultured in vitro.
The pinocytosis of 125I-labelled poly(vinylpyrrolidone), [14C]sucrose and colloidal [198Au]gold by rat yolk sac cultured in vitro.
复制标题
体外培养的大鼠卵黄囊对 125I 标记的聚（乙烯基吡咯烷酮）、[14C]蔗糖和胶体[198Au]金的胞饮作用。
作者：
A. Roberts;K. E. Williams;J. Lloyd
本文研究了体外培养17.5天的大鼠卵黄囊对~(125)I标记的聚(乙烯基吡咯烷酮)、~(14)C蔗糖和~(198)Au胶体金的摄取速率。在6.5h的时间内，每个底物以大约恒定且可重复的速度积累。2每毫克蛋白质微升/小时。这三种物质在体外积累后，以较低的速率从组织中释放到无底物的介质中。当蔗糖浓度达到10 mg/ml时，对[14C]蔗糖和~(125)I标记的聚(乙烯基吡咯烷酮)的积累都没有影响，但在较高浓度时抑制了这两种底物的吸收。一些批次的胶体[198Au]金具有显著更高的内吞指数(每毫克蛋白质高达5微升/小时)。该批次的内吞指数随底物浓度的增加而降低，但胶体金并不降低125I标记的聚乙烯吡咯烷酮的内吞指数。结果表明，三种底物均以胞饮作用进入卵黄囊。这些具有较高内吞指数的胶体[198Au]金也被认为是通过在膜结合部位上的吸附进入的。
The rates of uptake of 125I-labelled poly(vinylpyrrolidone), [14C]sucrose and colloidal [198Au]gold by 17.5-day rat yolk sac cultured in vitro were studied. Over a 6.5h period each substrate was accumulated at a constant and reproducible rate of approx. 2microliter/h per mg of protein. After accumulation in vitro, the three substances were released from the tissue into substrate-free medium at low rates. Sucrose present in the medium at concentrations up to 10 mg/ml was without effect on the accumulation of either [14C]sucrose or 125I-labelled poly(vinylpyrrolidone), but at higher concentrations inhibited the uptake of both substrates. Some batches of colloidal [198Au]gold had a significantly higher Endocytic Index (up to 5 microliter/h per mg of protein). The Endocytic Index of such a batch decreased with increasing substrate concentration, but colloidal gold did not decrease the Endocytic Index of 125I-labelled poly(vinylpyrrolidone). It is concluded that the three substrates enter the yolk sac by pinocytosis in the liquid phase. Those batches of colloidal [198Au]gold with higher Endocytic Indices are considered to enter also by adsorption on membrane binding-sites.