鼻腔暴露與氣管灌注奈米氧化鋅微粒後動物體內肺部外鋅轉移情形研究

Extrapulmonary Translocation of Ultrafine Zinc Oxide Particles Following Nose-only Exposure and Intratracheal Instillation

張淳農(Chun-Nung Chang)

指導教授 ： 黃耀輝

國立臺灣大學/公共衛生學院/職業醫學與工業衛生研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.01950

摘要

奈米氧化鋅被廣泛的應用在工業以及生產上，其大量的生產也造成了工人在製造、包裝及運輸過程中的暴露機會。有研究指出，奈米微粒進入生物體內會引發發炎、血栓以及心血管疾病，甚至進一步穿透細胞間隙進入循環系統，透過再分佈到達體內各器官、組織。本研究的目的在應用微透析技術連續採樣的優點，探討氧化鋅在動物循環系統的濃度變化情形。以及氣管灌注奈米氧化鋅至動物體內後，氧化鋅在器官、組織間的分布情形，並以此作為後續氧化鋅相關健康危害研究的基礎。
本研究使用七週大之 Sprague-Dawley 雄鼠，實驗分為呼吸暴露以及氣管灌注實驗兩個部份進行。微透析採樣部份以鼻腔暴露方式暴露於乾淨空氣1小時後 接續暴露50 nm 級之氧化鋅微粒4小時，暴露期間以微透析進行血液透析液連續採樣。第二部份將市售奈米氧化鋅及細微粒氧化鋅利用氣管灌注方式暴露至老鼠體內，每組實驗動物三隻，劑量為 5mg/kg，並在暴露後3小時、6小時、12小時、24小時分批進行犧牲，取得血清、血漿、全血、心臟、肺臟、肝臟、腎臟樣本，經微波消化後以感應耦合電漿質譜儀定量分析鋅濃度。
微透析透析液分析結果顯示，在體外實驗的回收率僅有4.3 %，在不同批次的實驗當中透析液的鋅濃度也未隨時間出現明顯變化趨勢。實驗動物體內高鋅背景值也對實驗結果造成影響。氣管灌注的實驗結果指出，在奈米氧化鋅以及細微粒氧化鋅實驗動物當中血清、全血，以及肝臟的鋅濃度有隨時間上升的趨勢，其他如血漿、心、肺臟及腎臟樣本中之鋅含量則未觀察到明顯的變化。實驗動物暴露不同粒徑大小微粒後各個器官的鋅濃度分布的差異也未達統計顯著。
本研究結果指出應用微透析採樣技術於奈米氧化鋅暴露實驗採樣並不成功，且需要進一步的調整實驗參數、介質與透析溶液，改進微透析對氧化鋅微粒的回收率，再應用於將來的實驗當中。氣管灌注實驗中，動物體內鋅背景值干擾器官與組織的鋅濃度定量，血漿、心、肺臟及腎臟中鋅的濃度並無顯著變化，但血清中的鋅濃度變化支持了氧化鋅微粒進入循環系統的假設。另外，於肝臟觀察到明顯的鋅濃度提升，有可能是氧化鋅經由循環系統再進入肝臟。但另一推測是實驗動物在灌注的過程中將氧化鋅食入消化道所導致，這部份仍需進一步實驗證明肝臟中的氧化鋅來源。後續研究將應用同位素技術以及發展微透析技術於奈米氧化鋅在體內之分布來解決背景值以及動物體間差異性的影響。

關鍵字

氧化鋅 ； 奈米微粒 ； 微透析 ； 氣管灌注

並列摘要

Nano-sized zinc oxide was applied in industries extensively, and many workers are exposed to zinc oxide directly or indirectly in factories, production facilities, and in operation where zinc oxide was proceeded, used, disposed, or recycled concurrently. However, there are literatures indicating that nano-sized particles may induce inflammation, thrombosis and cardiovascular diseases, or even penetrate into systemic circulation and redistribute to secondary organs. In our study, the aims were set to explore the zinc translocation in systemic circulation, characterize the distributions of the zinc levels in rat organs after exposing to fine and ultrafine particles intratracheally, and provide relevant the parameters for further kinetics studies.
Seven-week old male Sprague-Dawley (SD) rats were used in this study. This study was conducted in two parts. In the first part, study animals were exposed to clean air for 1 hour and then exposed to airborne zinc oxide for 4 hours. Continuous microdialysis sampling was performed during the exposure experiment. On the other part, we intratracheally instilled ultrafine and fine zinc oxide particles of 50 nm and 325 Mesh, respectively, in PBS solution to the study animals at a dose of 5mg/kg, with three animals per group. Rats were sacrificed at 3, 6 ,12 and 24 hours post exposure, and the zinc concentrations in whole blood, plasma, serum, heart, lung, liver, kidney and dialysates of the study animals were determined by inductive coupled plasma mass spectrometry (ICP-MS) following the pretreatment process of freeze-drying and microwave digestion.
The results of microdialysis revealed that in vitro recovery rate for zinc oxide was only 4.3%, and no obvious trend for zinc levels in dialysate with times was observed. In addition, the high zinc background level in the study animal might interfere with the results of zinc analysis. In the part of intratracheal instillation study, zinc levels were found elevated in serum, whole blood and liver in both ultrafine and fine zinc oxide particle exposure groups. However, there was no obvious trend for plasma, heart, lung and kidney samples. The difference in zinc levels in organ and tissue samples between these two exposure groups was not statistically significant.
The results indicated the application of microdialysis in inhalation study was not successful in this study. The elevations of zinc levels in serum, liver with time after exposing to nano-sized zinc oxide particles intratracheally supported that the particle translocation happened to systemic circulation, although the trends were not obvious. The elevation of zinc level in liver is probably attributed to the systemic translocation. However, another speculation is attributed to the absorption from gastrointestinal system while intratracheal instillation. Further study needs to clarify the exposure routes for zinc oxide particulates. Isotope technology is considered to be applied in the future study to differentiate the inhaled zinc content during experimental study from the background levels in organism. In general, the findings in our study provided preliminary information on the distribution of nano-sized ZnO particle in experimental animals after inhalation exposure for risk assessment.

並列關鍵字

Zinc oxide ； nano-particle ； microdialysis ； intratracheal instillation

參考文獻

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