Koutsogiannaki Sophia, Evangelinos Nikolaos, Koliakos George, Kaloyianni Martha
Laboratory of Animal Physiology, Zoology Department, School of Biology, Faculty of Science, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece.
Aquat Toxicol. 2006 Jul 20;78(4):315-24. doi: 10.1016/j.aquatox.2006.04.004. Epub 2006 May 1.
The signaling mechanism induced by cadmium (Cd) and zinc (Zn) in gill cells of Mytilus galloprovincialis was investigated. Both metals cause an increase in *O2- production, with Cd to be more potent (216 +/- 15%) than Zn (150 +/- 9.5%), in relation to control value (100%). The metals effect was reversed after incubation with the amiloride analogue, EIPA, a selective Na+/H+ exchanger (NHE) inhibitor as well as in the presence of calphostin C, a protein kinase C (PKC) inhibitor. The heavy metals effect on *O2- production was mediated via the interaction of metal ions with alpha1- and beta-adrenergic receptors, as shown after incubation with their respective agonists and antagonists. In addition, both metals caused an increase in intracellular pH (pHi) of gill cells. EIPA together with either metal significantly reduced the effect of each metal treatment on pHi. Incubation of gill cells with the oxidants rotenone, antimycin A and pyruvate caused a significant increase in pHi (delta pHi 0.830, 0.272 and 0.610, respectively), while in the presence of the anti-oxidant N-acetyl cysteine (NAC) a decrease in pHi (delta pHi -0.090) was measured, indicating that change in reactive oxygen species (ROS) production by heavy metals affects NHE activity. When rosiglitazone was incubated together with either heavy metal a decrease in O2- production was observed. Our results show a key role of NHE in the signal transduction pathway induced by Zn and Cd in gill cells, with the involvement of ROS, PKC, adrenergic and PPAR-gamma receptors. In addition, differences between the two metals concerning NHE activation, O2- production and interaction with adrenergic receptors were observed.
研究了镉（Cd）和锌（Zn）在加利福尼亚贻贝鳃细胞中诱导的信号传导机制。与对照值（100%）相比，两种金属均会导致超氧阴离子（O2-）生成增加，其中Cd的作用更强（216±15%），高于Zn（150±9.5%）。在用氨氯吡脒类似物EIPA（一种选择性Na+/H+交换体（NHE）抑制剂）孵育后以及在蛋白激酶C（PKC）抑制剂钙磷蛋白C存在的情况下，金属的作用被逆转。重金属对O2-生成的影响是通过金属离子与α1-和β-肾上腺素能受体的相互作用介导的，这在与各自的激动剂和拮抗剂孵育后得到了证实。此外，两种金属均导致鳃细胞内pH（pHi）升高。EIPA与任何一种金属一起显著降低了每种金属处理对pHi的影响。用氧化磷酸化抑制剂鱼藤酮、抗霉素A和丙酮酸孵育鳃细胞会导致pHi显著升高（分别为ΔpHi 0.830、0.272和0.610），而在抗氧化剂N-乙酰半胱氨酸（NAC）存在的情况下，pHi降低（ΔpHi -0.090），这表明重金属引起的活性氧（ROS）生成变化会影响NHE活性。当罗格列酮与任何一种重金属一起孵育时，会观察到*O2-生成减少。我们的结果表明NHE在Zn和Cd诱导的鳃细胞信号转导途径中起关键作用，涉及ROS、PKC、肾上腺素能和过氧化物酶体增殖物激活受体γ（PPAR-γ）受体。此外，观察到两种金属在NHE激活、*O2-生成以及与肾上腺素能受体相互作用方面存在差异。
