Garcia C R, Ann S E, Tavares E S, Dluzewski A R, Mason W T, Paiva F B
Universidade de São Paulo, Instituto de Biociências, Departamento de Fisiologia, Brazil.
Eur J Cell Biol. 1998 Jun;76(2):133-8. doi: 10.1016/S0171-9335(98)80026-5.
Calcium uptake by permeabilized P. chabaudi malaria parasites was measured at the trophozoite stage to assess calcium accumulation by the parasite organelles. As determined with 45Ca2+, the total calcium in the parasite was found to be 11 pmoles/10(7) cells. When the K+/H+ uncoupling agent, nigericin was present, this level fell to 6.5 pmoles/10(7) cells. A similar regulatory mechanism operates in P. falciparum, since addition of nigericin to intact parasites in calcium free-medium resulted in a transient elevation of free calcium in the parasite cytosol, as judged by fluorescent imaging of single cells loaded with the calcium indicator fluo-3,AM. 7-Chloro-4-nitrobenz-2-oxa-1,3-diazole (NBD-Cl) and monensin, inhibitors of H+ ATPases and K+/H+ ionophore respectively, induced calcium elevation in fluo-3, AM-labeled intact P. chabaudi parasites. We conclude that malaria parasites utilize acidic intracellular compartments to regulate their cytosolic free calcium concentration.
在滋养体阶段测量了透化处理的查巴迪疟原虫对钙的摄取，以评估寄生虫细胞器对钙的积累情况。用45Ca2+测定发现，寄生虫中的总钙含量为11皮摩尔/10(7)个细胞。当存在K+/H+解偶联剂尼日利亚菌素时，该水平降至6.5皮摩尔/10(7)个细胞。恶性疟原虫中也存在类似的调节机制，因为在无钙培养基中向完整的寄生虫添加尼日利亚菌素会导致寄生虫细胞质中游离钙的短暂升高，这是通过对加载了钙指示剂fluo-3, AM 的单细胞进行荧光成像判断得出的。7-氯-4-硝基苯并-2-恶唑-1,3-二唑（NBD-Cl）和莫能菌素分别是H+ ATP酶和K+/H+离子载体的抑制剂，它们在fluo-3, AM标记的完整查巴迪疟原虫中诱导钙升高。我们得出结论，疟原虫利用酸性细胞内区室来调节其细胞质游离钙浓度。
