EFFECTS AND MECHANISMS OF ACTION OF IONOPHOROUS ANTIBIOTICS VALINOMYCIN AND SALINOMYCIN-NA ON BABESIA GIBSONI IN VITRO
EFFECTS AND MECHANISMS OF ACTION OF IONOPHOROUS ANTIBIOTICS VALINOMYCIN AND SALINOMYCIN-NA ON BABESIA GIBSONI IN VITRO
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DOI：
10.1645/ge-2036.1
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发表时间：
2009-12-01
影响因子：
1.3
通讯作者：
Takiguchi, Mitsuyoshi
中科院分区：
文献类型：
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作者：
Yamasaki, Masahiro;Nakamura, Kensuke;Takiguchi, Mitsuyoshi
2种离子性抗生素缬霉素和盐霉素-Na对感染低钾高钠正常犬红细胞（即完全缺乏Na、k - atp酶活性的LK红细胞）的巴贝斯虫具有体外抗菌活性。在含有10(-1)ng/ml缬霉素或10(2)ng/ml盐霉素na的培养基中孵育24小时后，gibsoni的寄生水平显著降低。在含有5 μ g/ml盐霉素钠的培养基中孵育4小时，大多数寄生虫被破坏。相反，当寄生虫感染含高钾低钠的犬红细胞（即HK红细胞）时，两种离子抗生素的体外抗菌活性似乎被削弱，这显然是由于宿主细胞的保护。因此，观察了离子性抗生素对LK和HK红细胞的不同影响。在LK红细胞中，细胞内钾、钠和三磷酸腺苷（ATP）的浓度没有改变，在含有每种离子性抗生素的培养基中孵育后没有观察到溶血。这些结果表明，这些离子抗生素不影响没有Na， k - atp酶的细胞，直接作用于gibsoni。在HK红细胞中，离子性抗生素增加细胞内钠浓度，降低细胞内钾和ATP浓度，引起明显的溶血。此外，当沃阿因抑制Na， k -ATP酶活性时，瓦霉素引起的胞内ATP浓度下降和HK红细胞溶血现象消失。这些结果表明，离子抗生素对细胞内阳离子浓度的改变导致Na， k -ATP酶的激活和细胞内ATP消耗的增加，细胞内ATP的消耗导致HK红细胞溶血。此外，在高钾培养基中培养LK红细胞中的gibsoni时，valinomycin的抗菌活性消失。这表明，在这些培养基中，寄生虫的细胞内阳离子浓度没有改变，并将保持不变。
Valinomycin and salinomycin-Na, 2 ionophorous antibiotics, exhibited in vitro antibabesial activities against Babesia gibsoni that infected normal canine erythrocytes containing low potassium (LK) and high sodium concentrations, i.e., LK erythrocytes, which completely lack Na,K-ATPase activity. The level of parasitemia of B. gibsoni was significantly decreased when the parasites were incubated in culture medium containing either 10(-1) ng/ml valinomycin or 10(2) ng/ml salinomycin-Na for 24 hr. Four-hour incubation in the culture medium containing 5 mu g/ml salinomycin-Na led to the destruction of most parasites. In contrast, when the parasites infected canine erythrocytes containing high potassium (HK) and low sodium concentrations, i.e., HK erythrocytes, the in vitro antibabesial activities of both ionophorous antibiotics seemed to be weakened, apparently due to the protection by the host cells. Therefore, differential influences of ionophorous antibiotics on LK and HK erythrocytes were observed. In LK erythrocytes, the intracellular concentrations of potassium, sodium, and adenosine triphosphate (ATP) were not modified, and hemolysis was not observed after incubation in the medium containing each ionophorous antibiotic. These results suggested that these ionophorous antibiotics did not affect cells without Na,K-ATPase, and directly affected B. gibsoni. In HK erythrocytes, the ionophorous antibiotics increased the intracellular sodium concentration, and decreased the intracellular potassium and ATP concentrations, causing obvious hemolysis. Additionally, the decrease of the intracellular ATP concentration and the hemolysis in HK erythrocytes caused by valinomycin disappeared when the activity of Na,K-ATPase was inhibited by ouabain. These results indicate that modification of the intracellular cation concentrations by the ionophorous antibiotics led to the activation of Na,K-ATPase and increased consumption of intracellular ATP, and that the depletion of intracellular ATP resulted in hemolysis in HK erythrocytes. Moreover, the antibabesial activity of valinomycin disappeared when B. gibsoni in LK erythrocytes were incubated in culture media containing high potassium concentrations. This showed that the intracellular cation concentration in the parasites was not modified in those media and would remain the same.