Đăng nhập
Tìm kiếm nâng cao
Tên bài báo
Tác giả
Năm xuất bản
Tóm tắt
Lĩnh vực
Phân loại
Số tạp chí

Bản tin định kỳ
Báo cáo thường niên
Tạp chí khoa học ĐHCT
Tạp chí tiếng anh ĐHCT
Tạp chí trong nước
Tạp chí quốc tế
Kỷ yếu HN trong nước
Kỷ yếu HN quốc tế
Book chapter
Tạp chí quốc tế 2016
Số tạp chí 176(2016) Trang: 151-160
Tạp chí: Aquatic Toxicology

Striped catfish (Pangasianodon hypophthalmus) are farmed intensively at high stocking densities in Viet-nam where they are likely to encounter environmental hypercapnia as well as occasional high levels ofaquatic nitrite. Nitrite competes with Clfor uptake at the branchial HCO3/Clexchanger, causing adrastic reduction in the blood oxygen carrying capacity through the formation of methaemoglobin andnitrosylhaemoglobin. Environmental hypercapnia induces a respiratory acidosis where the branchialHCO3/Clexchange activity is reduced in order to retain HCO3for pH recovery, which should lead to areduced nitrite uptake. To assess the effect of hypercapnia on nitrite uptake, fish were cannulated in thedorsal aorta, allowing repeated blood sampling for measurements of haemoglobin derivatives, plasmaions and acid-base status during exposure to 0.9 mM nitrite alone and in combination with acute and 48 hacclimated hypercapnia over a period of 72 h. Nitrite uptake was initially reduced during the hypercapnia-induced acidosis, but after pH recovery the situation was reversed, resulting in higher plasma nitriteconcentrations and lower functional haemoglobin levels that eventually caused mortality. This suggeststhat branchial HCO3/Clexchange activity is reduced only during the initial acid-base compensation,but subsequently increases with the greater availability of internal HCO3counter-ions as pH is compen-sated. The data further suggest that branchial Na+/H+exchange plays a significant role in the initial phaseof acid-base compensation. Overall, longer term environmental hypercapnia does not protect againstnitrite uptake in P. hypophthalmus, but instead enhances it. In addition, we observed a significant sizeeffect in nitrite accumulation, where large fish attained plasma [nitrite] above the ambient concentration,while small fish did not. Small P. hypophthalmus instead had significantly higher plasma [nitrate], andhaemoglobin concentrations, revealing greater capacity for detoxifying nitrite by oxidising it to nitrate.

Các bài báo khác
Số tạp chí 2(2016) Trang: 50-63
Tạp chí: International E-Journal for Research in ELT
Số tạp chí 6(2016) Trang: 222-241
Tạp chí: World Journal of Pharmacy and Pharmaceutical Sciences
Số tạp chí xxx(2016) Trang:
Tác giả: Nguyễn Duy Sang
Tạp chí: Journal of Taibah University for Science
Số tạp chí 38(5)(2016) Trang: 549-557
Tạp chí: Songklanakarin J. Sci. Technol.
Số tạp chí 5(4)(2016) Trang: 616-622
Số tạp chí 65(2016) Trang: 1929-1948
Tạp chí: Optimization
Số tạp chí 61(2016) Trang: 651-668

Vietnamese | English

Vui lòng chờ...