University of Alaska Fairbanks, Institute of Arctic Biology, 902 N Koyukuk Dr, Fairbanks, AK 99775-7000, USA.
Acta Vet Scand. 2011 Dec 7;53(1):66. doi: 10.1186/1751-0147-53-66.
Understanding mercury (Hg) distribution in blood and the importance of hair as an excretory pathway is critical for evaluating risk from long term dietary Hg exposure. The major objective of this study was to characterize changes in total Hg concentrations in specific blood compartments and hair over time due to long term piscivory.
Eight sled dogs (Canis lupus familiaris) were fed either a fish and kibble diet (n = 4), or a fish-free control diet (n = 4) for 12 weeks. Concentrations of Hg were monitored throughout the exposure period, and for 10 weeks post exposure, until Hg concentrations in all blood compartments of one of the exposed dogs dropped below detection limit. Additionally, foreleg hair was sampled during acclimation and weeks 0 and 12.
Hg was detected primarily in whole blood and packed cells, although it was sporadically detected at low concentrations in plasma and serum in two of the fish fed dogs. Dogs ingested an estimated average of 13.4 ± 0.58 μg Hg per kg body weight per day. Hg was detectable in whole blood and packed cells within a week of exposure. Detected concentrations continued to rise until plateauing at approximately 3-6 weeks of exposure at a mean of 9.2 ± 1.97 ng/g (ppb) in whole blood. Hg concentration decreased post exposure following 1st order elimination. The mean half-life (t1/2) in whole blood for Hg was 7 weeks. Mean Hg in hair for the fish-fed dogs at week 12 was 540 ± 111 ppb and was significantly greater (about 7-fold) than the Hg hair concentration for the control dogs. The hair to blood ratio for Hg in fish-fed dogs was 59.0 ± 7.6:1.
This study found the sled dog model to be an effective method for investigating and characterizing blood Hg distribution (whole blood, serum, plasma, packed cells) and toxicokinetics associated with a piscivorous diet, especially for Hg-exposed fur bearing mammals (such as polar bears). Although hair excretion and hair to blood Hg ratios were not similar to human concentrations and ratios, the sled dog toxicokinetics of Hg in blood, was more similar to that of humans than traditional laboratory animals (such as the rat).
了解血液中的汞（Hg）分布情况以及毛发作为排泄途径的重要性，对于评估长期饮食 Hg 暴露的风险至关重要。本研究的主要目的是描述由于长期摄食鱼类而导致的特定血液成分和毛发中总 Hg 浓度随时间的变化。
8 只雪橇犬（Canis lupus familiaris）分别喂食鱼和干饲料（n=4）或无鱼对照饮食（n=4）12 周。在整个暴露期间监测 Hg 浓度，并在暴露后 10 周内，直到其中一只暴露犬的所有血液成分中的 Hg 浓度降至检测限以下。此外，在适应期和第 0 周和第 12 周采集前肢毛发样本。
Hg 主要存在于全血和浓缩红细胞中，但在两只喂食鱼的犬的血浆和血清中偶尔也以低浓度检测到。犬每天每公斤体重摄入约 13.4±0.58μg Hg。暴露后一周内即可在全血和浓缩红细胞中检测到 Hg。浓度持续升高，直到暴露 3-6 周左右达到平台期，全血中的平均浓度为 9.2±1.97ng/g（ppb）。暴露后，Hg 浓度呈一级消除方式下降。全血中 Hg 的平均半衰期（t1/2）为 7 周。喂食鱼的犬在第 12 周的毛发中 Hg 浓度为 540±111ppb，明显高于对照组犬的 Hg 浓度（约 7 倍）。喂食鱼的犬的毛发与血液中 Hg 的比值为 59.0±7.6:1。
本研究发现，雪橇犬模型是一种研究和描述血液 Hg 分布（全血、血清、血浆、浓缩红细胞）以及与肉食性饮食相关的毒代动力学的有效方法，尤其是对于暴露于 Hg 的有毛哺乳动物（如北极熊）。尽管毛发排泄和毛发与血液中 Hg 的比值与人类的浓度和比值不同，但与传统的实验室动物（如大鼠）相比，雪橇犬血液中的 Hg 毒代动力学更类似于人类。
