Nitric oxide (NO) is a mediator and biomarker of pro- and anti-inflammatory processes. Excessive levels of NO for long periods have been associated with inflammation and tissue damage. The metabolism and synthesis of NO is usually measured indirectly, as metabolites and enzymes involved in reactions, often as the nitrite/nitrate (NOx) level. The aim of the present study was to measure the NOx levels in vital organs of juvenile silver catfish (Rhamdia quelen) exposed to various levels of eprinomectin in the water. The fish were exposed for 24 and 48 h to start concentration (0 h) of eprinomectin in water (0.0, 1.12, 1.80, and 3.97 μg/L). The eprinomectin concentrations in water were lower at 24 h (0.0, 0.85, 1.14, and 1.15 μg/L) and 48 h (0.0, 0.39, 0.69, and 1.28 μg/L), due to the process of eprinomectin metabolization. Subsequently, the fish were left for 48 h of recovery in eprinomectin-free water. NO levels were measured indirectly, as NOx levels in brain, liver, and gill tissue. Within 24 h of exposure, there was no significant increase in NOx levels in the organs evaluated at any of the concentrations tested. However, increases in NOx levels did occur at 48 h of exposure in all organs, particularly at the two highest concentrations of eprinomectin (1.80 and 3.97 μg/L). The transfer of fish to eprinomectin-free water did not result in reversal of NOx levels after 48 h of recovery, especially in fish that had been exposed to the two highest concentrations in the brain and liver tissues, and for the highest concentration in the gills. We conclude that silver catfish exposed to eprinomectin for up to 48 h present possible cerebral, hepatic, and branchial inflammatory process associated with increased tissue NOx levels, and that recovery for 48 h in water without antiparasitic is insufficient for the fish to recover from the poisoning.

一氧化氮（NO）是促炎和消炎过程的介质和生物标志物。长期过量的NO与炎症和组织损伤有关。NO的代谢和合成通常以亚硝酸盐/硝酸盐（NOx）的水平作为与反应有关的代谢产物和酶间接测量。本研究的目的是测量幼年cat鱼（Rhamdia quelen）重要器官中的NOx水平）暴露于水中各种浓度的埃普诺菌素。将鱼暴露24和48小时，以在水中将依普连菌素开始浓缩（0 h）（0.0、1.12、1.80和3.97μg/ L）。由于表皮中菌素的代谢过程，水中的表皮中菌丝素浓度在24 h（0.0、0.85、1.14和1.15μg/ L）和48 h（0.0、0.39、0.69和1.28μg/ L）较低。随后，将鱼在不含表柔和素的水中恢复48小时。NO水平作为大脑，肝脏和as组织中的NOx含量间接测量。在暴露的24小时内，在任何测试浓度下评估的器官中NOx含量均没有显着增加。但是，在所有器官中暴露48 h时，NOx的水平确实增加了，尤其是在两种最高浓度的依普连菌素（1.80和3.97μg/ L）下。鱼类恢复到无表柔和素的水中后，恢复48小时后并未导致NOx含量逆转，特别是在暴露于脑和肝组织中两个最高浓度且and中浓度最高的鱼类中。我们得出的结论是，暴露于埃普诺菌素长达48 h的银cat鱼可能存在与组织NOx水平升高有关的可能的脑，肝和分支炎症过程，并且在无抗寄生虫的水中恢复48 h不足以使鱼从中毒中恢复过来。