Prusch R D, Hannafin J A
J Gen Physiol. 1979 Oct;74(4):523-35. doi: 10.1085/jgp.74.4.523.
The relationship between Ca++ and pinocytosis was investigated in Amoeba proteus. Pinocytosis was induced with 0.01% alcian blue, a large molecular weight dye which binds irreversibly to the cell surface. The time-course and intensity of pinocytosis was monitored by following the uptake of [3H]SUCROSE. When the cells are exposed to 0.01% alcian blue, there is an immediate uptake of sucrose. The cells take up integral of 10% of their initial volume during the time-course of pinocytosis. The duration of pinocytosis in the amoeba is integral of 50 min, with maximum sucrose uptake occurring 15 min after the induction of pinocytosis. The pinocytotic uptake of sucrose is reversibly blocked at 3 degrees C and a decrease in pH increases the uptake of sucrose by pinocytosis. The process of pinocytosis is also dependent upon the concentration of the inducer in the external medium. The association between Ca++ and pinocytosis in A. proteus was investigated initially by determining the effect of the external Ca++ concentration on sucrose uptake induced by alcian blue. In Ca++-free medium, no sucrose uptake is observed in the presence of 0.01% alcian blue. As the Ca++ concentration is increased, up to a maximum of 0.1 mM, pinocytotic sucrose uptake is also increased. Increases in the external Ca++ concentration above 0.1 mM brings about a decrease in sucrose uptake. Further investigations into the association between Ca++ and pinocytosis demonstrated that the inducer of pinocytosis displaces surface calcium in the amoeba. It is suggested that Ca++ is involved in two separate stages in the process of pinocytosis; an initial displacement of surface calcium by the inducer which may increase the permeability of the membrane to solutes and a subsequent Ca++ influx bringing about localized increases in cytoplasmic Ca++ ion activity.
在大变形虫中研究了钙离子（Ca++）与胞饮作用的关系。用0.01%的阿尔新蓝诱导胞饮作用，阿尔新蓝是一种与细胞表面不可逆结合的大分子染料。通过追踪[3H]蔗糖的摄取来监测胞饮作用的时间进程和强度。当细胞暴露于0.01%的阿尔新蓝时，蔗糖会立即被摄取。在胞饮作用的时间进程中，细胞摄取的液体体积相当于其初始体积的10%。大变形虫胞饮作用的持续时间为50分钟，蔗糖摄取量在胞饮作用诱导后15分钟达到最大值。蔗糖的胞饮摄取在3摄氏度时可逆性受阻，pH值降低会增加蔗糖的胞饮摄取量。胞饮作用的过程也取决于外部培养基中诱导剂的浓度。最初通过确定外部钙离子浓度对阿尔新蓝诱导的蔗糖摄取的影响，研究了大变形虫中钙离子与胞饮作用的关系。在无钙离子的培养基中，在0.01%的阿尔新蓝存在下未观察到蔗糖摄取。随着钙离子浓度增加，直至最大0.1 mM，胞饮性蔗糖摄取也增加。外部钙离子浓度高于0.1 mM时，蔗糖摄取量会下降。对钙离子与胞饮作用关系的进一步研究表明，胞饮作用的诱导剂会取代变形虫表面的钙。有人提出，钙离子在胞饮作用过程中涉及两个不同阶段；诱导剂最初取代表面钙，这可能会增加膜对溶质的通透性，随后钙离子内流导致细胞质钙离子活性局部增加。
