Garcia C R, Dluzewski A R, Catalani L H, Burting R, Hoyland J, Mason W T
Departamento de Parasitologia, Universidade de São Paulo, Brazil.
Eur J Cell Biol. 1996 Dec;71(4):409-13.
The fluorescent indicator, fura-2, AM, was used to measure free calcium concentrations in the intraerythrocytic malaria parasites of Plasmodium chabaudi and Plasmodium falciparum. In both species the free cytosolic calcium concentration was maintained at low levels (between 40 and 100 nM throughout the maturation process. Digital image analysis of the indicator fluorescence was performed on parasites and evaluated with the aid of a calibration of the calcium response, based on permeabilized parasites, exposed to calcium buffers. This again revealed that free calcium concentrations in the intact parasite are maintained at a predetermined level, regardless of the free calcium in the surrounding milieu. Both species of parasites are thus capable of regulating their internal free calcium levels with high precision, presumably by means of calcium pump ATPases. A small but significant elevation of the cytosolic free calcium concentration by the tumor promoter, thapsigargin, may be taken to reflect the presence of calcium stores in the endoplasmic reticulum in P. falciparum.
荧光指示剂fura-2 AM被用于测量查巴迪疟原虫和恶性疟原虫红细胞内疟原虫的游离钙浓度。在这两个物种中，游离胞质钙浓度在整个成熟过程中都维持在低水平（40至100 nM之间）。对寄生虫的指示剂荧光进行数字图像分析，并基于暴露于钙缓冲液的通透寄生虫的钙反应校准进行评估。这再次表明，完整寄生虫中的游离钙浓度维持在预定水平，而与周围环境中的游离钙无关。因此，这两种寄生虫都能够通过钙泵ATP酶高精度地调节其内部游离钙水平。肿瘤促进剂毒胡萝卜素使胞质游离钙浓度有小幅但显著的升高，这可能反映了恶性疟原虫内质网中存在钙储存。
