液相色谱-三重四级杆复合线性离子阱质谱法分析恩诺沙星在鲤鱼(Cyprinus carpio)中的代谢产物

采用液相色谱-三重四级杆复合线性离子阱质谱(HPLC/Q-TRAP MS),在正离子检测模式下,对鲤鱼(Cyprinus carpio)腹腔注射恩诺沙星给药后肝脏中的代谢产物进行分析。根据保留时间和各色谱峰质谱裂解规律,推测了恩诺沙星在鲤鱼肝脏中的代谢产物,同时,根据二级质谱碎片离子推测代谢途径及代谢产物结构。结果显示,恩诺沙星进入鲤鱼肝脏后,除以恩诺沙星原形药物(M0)和N-去乙基代谢产物环丙沙星(M2)形式存在外,还有少量恩诺沙星脱羧代谢产物(M1)和恩诺沙星羟基化代谢产物(M3-1和M3-2)。该研究可为深入了解恩诺沙星在水生动物体内代谢产物及代谢机理提供理论基础,为在水产养殖生产中科学、合理地使用恩诺沙星提供参考。     

恩诺沙星在凡纳滨对虾体内和体外肝微粒体中的代谢产物比较分析

采用超高效液相色谱-四级杆-飞行时间质谱(UPLC/Q-TOF MS)对恩诺沙星在凡纳滨对虾(Litopenaeus vannamei)体内和体外肝胰腺微粒体孵育下的代谢产物进行定性分析。体内试验为凡纳滨对虾口灌30 mg.kg-1恩诺沙星,24 h后采集血浆用于代谢产物分析。体外试验为在含有肝微粒体的NADPH体系中加入恩诺沙星(100μM)进行孵育,检测孵育液中的代谢产物;肝胰腺采集自未给药的凡纳滨对虾,超速离心法制备而得。凡纳滨对虾血淋巴中除以恩诺沙星原形药物为主外,还可检测到少量的N-去乙基代谢产物环丙沙星、环丙沙星哌嗪环开环代谢物及其同分异构体;而在肝胰腺微粒体体外孵育体系中除检测到原形药物外,只有少量的N-去乙基代谢物环丙沙星。无论是体内还是体外,代谢产物生成量都很少,但环丙沙星是主要代谢产物。推测恩诺沙星在凡纳滨对虾体内的代谢反应主要是脱乙基反应和加氢还原反应,而在体外肝胰腺微粒体恩诺沙星代谢的反应主要是脱乙基反应。     

采用LC/MS~n法分析恩诺沙星在锯缘青蟹血浆中的代谢产物

采用电喷雾离子阱质谱法在正离子检测方式下,对锯缘青蟹口灌恩诺沙星给药后血淋巴中恩诺沙星和代谢产物进行定性分析。通过对血浆中恩诺沙星及其代谢产物的质谱裂解行为进行碰撞诱导解离分析,获得了各化合物的多级质谱信息,通过比较各化合物结构和质谱裂解途径的异同点,发现有三个代谢产物,其中峰面积最大的为环丙沙星,其次为羟基化恩诺沙星,另一代谢产物可能是加氧恩诺沙星;推测恩诺沙星在锯缘青蟹体内的代谢反应主要是脱乙基反应、羟基化反应和氧化反应。通过定量分析,血浆中恩诺沙星和代谢产物环丙沙星的浓度分别为19.1μg/ml和0.526μg/ml。     

药浴给药恩诺沙星及其代谢产物在欧洲鳗鲡体内的药代动力学研究

应用反相高效液相色谱法,研究药浴给药条件下,恩诺沙星及其代谢产物环丙沙星在欧洲鳗鲡体内的药代动力学.按10mg·L-1药浴给药后,恩诺沙星在欧洲鳗体内各组织器官中分布可用开放性二室模型来描述.血浆、肌肉、肝脏和肾脏中恩诺沙星达峰时间分别为44.27h、42.74h、50.69h、95.80h,以后开始缓慢下降,血浆、肌肉、肝脏和肾脏中代谢产物环丙沙星达峰时间分别为48.89h、55.34h、54.64h、100.0h.给药3个月后血浆、肌肉、肝脏和肾脏中的恩诺沙星浓度分别为0.0844μg·mL-1、0.09959μg·g-1、0.01242μg·g-1、3.7164u·g-1;恩诺沙星在血浆、肌肉、肝脏和肾脏中的消除半衰期(T1/2β)分别为908.07h、901.24h、59.32h、767.81h.鉴于恩诺沙星和其代谢产物环丙沙星在欧洲鳗鲡体内消除较慢,建议养成阶段不使用此药.     

恩诺沙星在养殖大菱鲆体内的残留及消除规律

在11～12 ℃水温条件下,对大菱鲆Scophthalmus maximus连续口服恩诺沙星7 d后肌肉、血清和肝脏组织中该药物及其代谢产物环丙沙星的残留及消除规律进行了研究.大菱鲆肌肉、血清和肝脏中残留的恩诺沙星药物用二氯甲烷提取,在不同的时间点利用反相高效液相色谱荧光检测法检测药物浓度,最低检测限为0.01 μg/ml,平均回收率为75%～87%.研究结果表明,恩诺沙星按一级动力学过程从体内消除,在3种组织中消除速率不同,在肌肉、血清和肝脏中的消除曲线方程分别为C=1.560e-0.0310 t、C=1.147e-0.018 9 t和C=0.920e-0.027 1 t;恩诺沙星在3种组织中的消除半衰期较长,分别为22.53、36.67和25.57 d.在给药后的第94天,肌肉组织中的恩诺沙星浓度持续保持0.168 μg/g,尽管NY5070-2002无公害水产食品中恩诺沙星和环丙沙星的残留限量MRL(Maximum residue limit)要求为0.05 μg/g,但本试验数据提示,大菱鲆肌肉组织中残留的恩诺沙星和环丙沙星超过了标准,建议合理的休药期应不少于120 d.     

喹噁啉类药物及其代谢产物在刺参体内的分析和鉴定

采用液相色谱-三重四极杆线性离子阱串联复合质谱(LC-MS/MS-Qtrap)分析和鉴定海参中喹噁啉类及其代谢物的结构。采用C18色谱柱分离,以0.1%甲酸水溶液-甲醇为流动相,梯度洗脱,质谱采集使用预设定多反应监测(s MRM)-信息依赖性采集(IDA)-增强子离子扫描(EPI)模式。海参按10μg/m L质量浓度分别进行喹乙醇、乙酰甲喹和喹烯酮药浴,整只取样进行测定。采用Analyst 1.6软件进行数据处理,根据保留时间和各色谱峰质谱裂解规律,比较确定喹噁啉类的主要代谢产物,同时根据质谱二级裂解规律对代谢产物结构进行推测。结果显示,3-甲基喹噁啉-2-羧酸(MQCA)、N4-还原喹乙醇(Q5)和脱二氧喹乙醇(Q6)是喹乙醇在海参中的主要代谢产物,MQCA、N1-脱氧羰基还原乙酰甲喹(Q1)、脱二氧乙酰甲喹(Q2)和脱二氧羰基还原乙酰甲喹(Q3)是乙酰甲喹在海参中的主要代谢产物,MQCA、脱二氧喹烯酮(Q4)和N1-脱氧喹烯酮(Q7)是喹烯酮在海参中的主要代谢产物。本研究建立了喹噁啉类及其代谢物的标准EPI谱库,实现了对海参样品中喹噁啉类及其代谢物残留量高灵敏的准确定性分析。     

恩诺沙星及其代谢产物环丙沙星在牙鲆体内代谢消除规律

以80 mg/kg鱼体重对牙鲆单次口灌给药恩诺沙星,给药后在不同的时间点取样,用高效液相色谱荧光检测器检测,研究恩诺沙星及其主要代谢产物环丙沙星在牙鲆体内的代谢消除规律。研究表明,停药后0.25 h,肌肉中恩诺沙星残留量最低。各组织的消除半衰期依次为腮肝脏血液肾脏肌肉,其中肌肉中恩诺沙星消除半衰期最低为67.759 h,消除最快,停药后12 d检测不到恩诺沙星。停药后0.25 h,在牙鲆血液、肝脏、肾脏中均有环丙沙星残留,残留量依次为肝脏肾脏血液,肌肉和鳃中未检出环丙沙星。停药后22 d在血液、肝脏和肾脏3个组织中仍然能够检测出恩诺沙星,但是停药7 d后这3个组织中均检测不出环丙沙星。结果显示,恩诺沙星在牙鲆体内代谢速度较慢,而且只是在一段时间内有脱乙基代谢为环丙沙星的反应发生,但并不是在恩诺沙星消除的全过程都发生,而且代谢物环丙沙星在牙鲆体内的消除速度要比恩诺沙星快。     

恩诺沙星乳在罗非鱼体内的药代动力学及组织分布

为研究恩诺沙星乳新剂型及其去乙基代谢产物环丙沙星在罗非鱼(Oreochroms mossambcus)血浆中的药代动力学及分布,在(30±1)℃养殖水温下,对罗非鱼单次口灌10 mg/kg恩诺沙星乳,在0.5、1、2、4、6、8、12、18、24、48、72、96、120、144、168 h取样,样品处理后以超高效液相色谱荧光检测器检测。研究显示:恩诺沙星在罗非鱼血浆中的达峰时间(T_(max))为2 h,峰浓度(C_(max))为4.38 mg/L;环丙沙星在罗非鱼血浆中的T_(max)为8 h,C_(max)为0.1 mg/L;恩诺沙星在罗非鱼肝、脑、肌肉、肾中的T_(max)分别为1、2、4和6 h,C_(max)分别为12.37、4.31、6.22和7.82 mg/kg,消除方程分别为C=3.96e~(-0.0232t)、C=7.52e~(-0.0253t)、C=6.04e~(-0.015t)、C=2.73e~(-0.0205t);环丙沙星在罗非鱼肝、肌肉、肾中的T_(max)分别为4、6和6 h,C_(max)分别为0.39、0.15和0.23 mg/kg,消除方程分别为C=0.11e~(-0.0186t)、C=0.29e~(-0.0184t)、C=0.17e~(-0.0132t)。结果表明,恩诺沙星乳在罗非鱼体内吸收迅速,大部分以恩诺沙星原药代谢出体外,仅有3.22%～6.03%恩诺沙星被代谢成环丙沙星,虽然环丙沙星含量低但在罗非鱼体内比恩诺沙星更难消除;建议罗非鱼以10 mg/kg口灌恩诺沙星乳用于疾病的防治。     

恩诺沙星及其代谢产物在珍珠龙胆石斑鱼(Epinephelus fuscoguttatus ♀×Epinephelus lanceolatus ♂)体内的代谢及消除规律

本研究在连续给药的情况下,开展恩诺沙星及其代谢产物环丙沙星在珍珠龙胆石斑鱼体内的代谢残留情况研究,为科学合理使用恩诺沙星防治珍珠龙胆石斑鱼的细菌性疾病提供理论依据,也在水产养殖上为指导恩诺沙星科学用药提供借鉴。在28℃的水温条件下,以30 mg/(kg·bw)恩诺沙星对平均体重为(300±28)g的珍珠龙胆石斑鱼进行连续5 d口灌给药实验,用高效液相色谱-串联质谱法测定石斑鱼血浆、肌肉和肝脏中恩诺沙星及其代谢产物环丙沙星的残留含量。结果显示:恩诺沙星在血浆、肝脏和肌肉中很快达到最大值,达峰时间分别为第5天给药后3 h、第5天给药后3 h和第4天给药后3 h,其浓度分别为24.5 mg/L、13.0 mg/kg和8.20 mg/kg;恩诺沙星的代谢产物环丙沙星分别在第5天给药后3 h、第5天给药后3 h和第4天给药后3 h达到峰值,其浓度分别为0.276 mg/L、0.738 mg/kg和0.110 mg/kg,说明只有少量的恩诺沙星代谢成环丙沙星。根据本实验的数据,建议休药期不低于980度日。     

异育银鲫肝微粒体体外恩诺沙星N-脱乙基酶酶促反应动力学初步研究

建立了异育银鲫肝微粒体体外孵育恩诺沙星(enrofloxacin,EF)的酶促反应体系,应用RP-HPLC法检测其主要代谢产物环丙沙星(ciprofloxacin,CF),以间接反映恩诺沙星N-脱乙基酶的活性。采用二氯甲烷提取、正已烷去脂提取有效成分,样品回收率均大于81.4%,含CF或EF的肝微粒体样品能在4℃下稳定至少72 h,日内变异系数不超过3.51%,日间变异系数不超过3.71%,EF和CF准确度分别小于8.1%、6.5%,检测限(信超比为3)分别为0.15μmol/L、0.3μmol/L。恩诺沙星在银鲫肝微粒体中代谢符合一级消除方程C=140e-0.072t,消除速率常数(K)为0.072/h,消除半衰期(T1/2)为9.627 h。用Origin Lab软件的Hyperbl模型进行拟和,以方程y=P1.x/(P2+x)表示米氏常数Vmax、Km两者的关系,求得Vmax为0.2602±0.0147nmol/mg.min,Km为53.8985±10.2257μmol/L,内在清除率(Clint)约为0.0048 mL/(min.mg)。恩诺沙星消除率和环丙沙星转化率的研究结果提示,恩诺沙星在银鲫肝微粒体中的代谢以N-脱乙基反应为主,提示可能还通过其它途径生成另外代谢产物。而酶动力学研究数据(Vmax,Clint值)表明,恩诺沙星N-脱乙基酶与底物结合力不强,酶促反应强度处于中等水平。据此,笔者推测恩诺沙星在银鲫肝微粒体中的代谢速度较为缓慢。     

Pharmacokinetics and the active metabolite of enrofloxacin in Chinese mitten-handed crab (Eriocheir sinensis)

The pharmacokinetics and active metabolite of enrofloxacin were estimated after single intramuscular administration (10.0 or 20.0 mg/kg body weight) to the Chinese mitten-handed crab (Eriocheir sinensis) in fresh water at 25.0 ± 1.0 °C. Levels of enrofloxacin and its metabolite ciprofloxacin in the main tissues (hemolymph, hepatopancreas, muscle, ovary and spermary) were simultaneously detected by HPLC. Enrofloxacin concentration–time profiles for the hemolymph in both tests were described by a two-compartment open model with first-order absorption. Distribution half-time (T_1/2), elimination half-time (T_1/2β), body clearance (CL/F), mean residence time (MRT_0–∞), area under the concentration–time curve from 0 to ∞ h (AUC_0–∞) and apparent volume of distribution (Vd/F), which derived from the pharmacokinetic model, were 0.427 h, 21.3 h, 0.133 l/h/kg, 60.0 h, 96.9 μg/ml/h and 4.08 l/kg, respectively, at a dose of 10.0 mg/kg body weight, and 0.216 h, 12.3 h, 0.189 l/h/kg, 85.8 h, 187 μg/ml/h and 3.35 l/kg, respectively, at a dose of 20.0 mg/kg body weight. Similarities were found between the hemolymph concentration–time curves of the two tests; for example, instant absorption process followed by the distribution phrase, and a second absorption peak at 6 h post-treatment. After intramuscular administration of 10.0 mg/kg body weight, absorption of enrofloxacin was observed in the main edible tissues (hepatopancreas, muscle, ovary and spermary), and the drug residue was the highest in the hepatopancreas, where the ‘drug sink’ phenomenon occurred. Comparative pharmacokinetics showed fast absorption, broad distribution and fast elimination of enrofloxacin in E. sinensis after intramuscular dosing. Regarding ciprofloxacin, the main active metabolite of enrofloxacin, though relatively low levels were detected in all the main tissues of the crab, its kinetics in the hemolymph in the two tests were not described by a one- or two-compartment open model.     

恩诺沙星在大菱鲆(Scophthalmus maximus)、牙鲆(Paralichthys olivaceus)和半滑舌鳎(Cynoglossus semilaevis)体内的残留消除规律

本研究比较了在20℃水温条件下恩诺沙星(Enrofloxacin)在3种主要养殖鲆鲽鱼[大菱鲆(Scophthalmus maximus)、牙鲆(Paralichthys olivaceus)和半滑舌鳎(Cynoglossus semilaevis)]体内的残留消除规律。选择体重为300–400 g 的健康2龄大菱鲆、牙鲆和半滑舌鳎，以10 mg/kg 的剂量连续3 d 通过灌胃的方式分别给予恩诺沙星后，于1、3、6、10、15、20、25、30、35、40 d 采集血浆、肝、鳃、肌肉和肾组织。利用高效液相色谱法检测血浆和各组织中的恩诺沙星浓度，拟合恩诺沙星在3种鲆鲽鱼体内的消除曲线，计算消除半衰期。结果显示，3种鲆鲽鱼的组织中，恩诺沙星在肾中残留浓度最高，其消除速度依次为牙鲆>大菱鲆>半滑舌鳎，其消除半衰期分别为3.75、6.54、7.37 d；恩诺沙星在大菱鲆、牙鲆和半滑舌鳎血浆中的消除比其代谢产物环丙沙星慢；综合比较恩诺沙星在3种鲆鲽鱼血浆和大多数组织中的消除规律，均呈现出牙鲆体内消除最快，大菱鲆次之，半滑舌鳎最慢的趋势。依据我国无公害水产品中恩诺沙星最高残留限量为50μg/kg 的标准，建议在20℃水温条件下使用恩诺沙星防治鲆鲽鱼细菌性疾病时的休药期为：大菱鲆44 d、牙鲆33 d、半滑舌鳎47 d 以上。     

Pharmacokinetics of enrofloxacin and its metabolite ciprofloxacin in healthy and Vibrio alginolyticus-infected large yellow croaker (Pseudosciaena crocea)

The present study was designed to explore pharmacokinetics of enrofloxacin and its metabolite ciprofloxacin in healthy and Vibrio alginolyticus-infected large yellow croaker (Pseudosciaena crocea) after a single 10 mg/kg oral dose. Concentrations of enrofloxacin and ciprofloxacin in serum, liver, kidney, muscle and skin of fish were determined using high-performance liquid chromatography. Pharmacokinetic parameters were analysed based on classical compartmental model analysis. The overall changes in enrofloxacin concentration–time curves in serum and tissues of diseased fish were similar to those of healthy fish. However, the peak concentration and peak time of enrofloxacin in serum and tissues were different in healthy and diseased fish. A delay of enrofloxacin peak time in serum and all tissues appeared in the diseased fish. The peak concentrations in serum and tissues of the diseased fish were lower than those of healthy fish. In healthy fish, the area under the concentration–time curve (AUC) was in the order serum >liver > kidney >muscle > skin, while AUC was serum >live > muscle >kidney > skin in the diseased fish. The peak concentrations of ciprofloxacin in the liver, serum, kidney, muscle and skin of healthy fish were 0.93 μg/g, 0.55 μg/ml, 0.36 μg/g, 0.37 μg/g and 0.12 μg/g respectively. T_max of ciprofloxacin in the corresponding tissues was 8, 24, 12, 12 and 16 h respectively. In the diseased fish, the peak concentrations of ciprofloxacin in the corresponding tissues were 0.52 μg/g, 0.52 μg/ml, 0.41 μg/g, 0.27 μg/g and 0.13 μg/g respectively. T_max in the corresponding tissues were 0.5, 8, 12, 16 and 48 h respectively. These data indicate that the health status of fish affects drug absorption and metabolism.     

恩诺沙星及其代谢产物在中华绒螯蟹血淋巴中的比较药代动力学

研究了不同水温(16℃、25℃)、不同给药剂量(10 mg/kg、20 mg/kg)和不同给药方式(肌注、口灌)等条件下,恩诺沙星及其代谢产物环丙沙星在中华绒螯蟹体内的药代动力学,比较了不同条件下药物在蟹血淋巴中的吸收、分布和代谢的差异。结果表明,恩诺沙星在蟹血淋巴中的药-时数据符合开放式二室模型。16℃时以10 mg/kg剂量肌注给药后,恩诺沙星在蟹血淋巴的主要药代动力学参数为:AUC96.818 mg/(L.h),Cmax6.54μg/mL,t1/2α0.851 h,t1/2β95.415 h;25℃时以10 mg/kg剂量肌注给药后,恩诺沙星的主要药代动力学参数为:AUC168.457 mg/(L.h),Cmax7.12μg/mL,t1/2α0.58h,t1/2β88.833 h;25℃时以20 mg/kg剂量肌注给药后,恩诺沙星的主要药代动力学参数为:AUC155.612 mg/(L.h),Cmax11.045μg/mL,t1/2α5.239h,t1/2β88.378 h;25℃时以10 mg/kg剂量口灌给药后,恩诺沙星的主要药代动力学参数为:AUC86.525 mg/(L.h),Cmax3.469μg/mL,t1/2α8.071h,t1/2β61.842 h。不同条件下,恩诺沙星在蟹血淋巴中的主要药代动力学参数差异较大。恩诺沙星的活性代谢产物环丙沙星在各种给药条件下的蟹血淋巴中均能检出,但含量均处于较低值,且药-时数据不能用房室模型拟合,表明恩诺沙星在蟹体内只有极少部分代谢为环丙沙星。     

恩诺沙星及其代谢产物环丙沙星在拟穴青蟹体内的药代动力学

采用高效液相色谱法,研究盐度33条件下恩诺沙星口灌和肌肉注射给药(剂量10 mg/kg)后,恩诺沙星及其代谢物环丙沙星在拟穴青蟹体内的药代动力学和组织分布。血淋巴和组织中药代动力学参数采用基于统计矩原理的非房室模型进行计算。恩诺沙星口灌和肌肉注射拟穴青蟹给药后,血药达峰快,分别为0.5 h和1 min,达峰浓度分别为12.90和31.86 μg/mL,曲线下面积(AUC)分别为216.1和816.8 μg/(mL·h)。恩诺沙星在拟穴青蟹组织中分布较广,口灌给药下肌肉和肝胰腺AUC分别为445.9和817.6 μg/(g·h),肌肉注射给药下的AUC分别为554.7和2 573.7 μg/(g·h)。与其它水产动物相比,恩诺沙星在拟穴青蟹体内消除速度为中等水平,口灌和肌肉注射恩诺沙星后血药消除半衰期(t_1/2z)分别为26.45和57.02 h,总体清除率(CL_z)分别为0.054和0.012 L/(h·kg)。恩诺沙星在拟穴青蟹体内代谢生成环丙沙星的量较少,口灌给药下血淋巴、肌肉和肝胰腺的AUC_CIP/AUC_ENR分别为6.66%、3.66%和4.78%,肌肉注射给药下,其相应值分别为4.16%、7.24%和1.48%,在拟穴青蟹体内起药效作用仍是以恩诺沙星为主。以C_max/MIC、AUC_0-24/MIC评价恩诺沙星在青蟹体内的药效作用,建议给拟穴青蟹以10 mg/kg剂量每隔24小时投喂一次恩诺沙星,对弧菌引起的细菌性疾病具有较好的防治效果。     

Tissue Distribution of Enrofloxacin in Fingerling Rainbow Trout Oncorhynchus mykiss Following Different Doses of Oral Administration

Rainbow trout Oncorhynchus mykiss were fed a ration medicated to provide enrofloxacin (Baytrilo®, Bayer) at 2.5, 5.0, or 10.0 mg drug per kg fish per d either 5 or 10 d. Tissue Concentrations of enrofloxacin were measured in liver, kidney, muscle, skin, and serum during the medication period, and thereafter for a total of 30 d. Highest tissue concentrations were observed in fish medicated with 5 mg enrofloxacin per kg fish per d for 10 d. Tissue concentrations of anitmicrobial activity were found to exceed minimum inhibitory concentrations of enrofloxacin for several isolates of Aeromonas salmonicida and Renibacterium salmoninarum . Lower than expected tissue concentrations were observed for the 10 mg per kg fish per d doses, perhaps due to a lack of acceptance of the medicated ration. The results support evaluation of a 5 mg per kg fish dose to treat bacterial infections of salmonids under field conditions.     

恩诺沙星对小体鲟和史氏鲟体内SOD活力影响的比较研究

在水温23℃、pH值6．5、溶氧10mg／L、氨氮含量小于0．1mg／L和亚硝酸盐含量小于0．001mg／L的条件下，将恩诺沙星按照0、20、40、60、80和100mg／kg浓度，连续口服给平均体重50．0±5．0g的小体鲟（Acipenser ruthenus Linnaeus）及史氏鲟（Acipenser schrenckii Brandt）5d，停药2d后测定其血浆及肝脏组织中过氧化物岐化酶SOD的活力，以期掌握不同恩诺沙星给药浓度下，两种鲟两种组织中SOD活力变化趋势，探讨分析该酶在药物代谢过程中的作用机制。结果表明：两种鲟两种组织内均含有一定量的SOD酶，且在对照组及所有给药组肝脏中酶活力均高于血浆中。不同给药浓度下，两种鲟两种组织中SOD活力均先受诱导升高，而后被抑制降低的变化趋势，且在40mg／kg浓度组达到最大值。血浆中SOD活力受给药浓度影响较小，起伏较平稳，而小体鲟SOD活力始终高于史氏鲟。肝脏中SOD活力变化较剧烈，在低浓度组（〈40mg／kg）史氏鲟肝脏中SOD活力明显高于小体鲟，而在高给药浓度组（〉40mg／kg）则小体鲟略高于史氏鲟。     

Winter Field Trials of Enrofloxacin for the Control of Aeromonas salmonicida Infection in Salmonids

The antimicrobial enrofloxacin (Baytril®, Bayer) was evaluated under field conditions in the winter months for treatment of clinical Aeromonas salmonicida infections in salmonids by feeding medicated diets. Two trials in which lake trout Salvelinus namaycush were treated with enrofloxacin at 10mg/kg per d for 10d resulted in reduced mortalities when compared to non-medicated controls. A third trial in which Atlantic salmon Salmo salar were treated required 20d for the fish to consume the 10d medicated ration, due to poor feeding. This resulted in an effective dose of 5mg/kg per d for 20d. In spite of the lower feeding activity, a reduction in mortalities in medicated fish was observed. Tissue concentrations of drug were in excess of minimum inhibitory concentrations of the drug for the A. salmonicida isolates tested.