Accumulation of ammonia in the body and NH3 volatilization from alkaline regions of the body surface during ammonia loading and exposure to air in the weather loach Misgurnus anguillicaudatus
T. K. N. Tsui1,
D. J. Randall2,*,
S. F. Chew3,
Y. Jin1,
J. M. Wilson4 and
Y. K. Ip1
1 Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Road, Singapore 117543, Republic of Singapore,
2 Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China,
3 Department of Natural Sciences, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore and
4 Centro Interdisciplinar de Investigacao Marinha e Ambiental-CIIMAR, Rua do Campo Alegre 823, 4150-180 Porto, Portugal

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Fig. 1. (A) Effects of various periods of ammonia exposure (30 mmol l1 NH4Cl) on the concentrations of ammonia (A) and urea (B) in the blood plasma (open columns), liver (hatched columns) and muscle (filled columns) of Misgurnus anguillicaudatus. Values are means + S.E.M. (N=6). aSignificantly different from the 0 h/C condition, P<0.05; bsignificantly different from the 12 h/N condition, P<0.05; csignificantly different from the 24 h/N condition, P<0.05; dsignificantly different from the 48 h/N condition, P<0.05. N, 30 mmol l1 NH4Cl; C, control.
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Fig. 2. Effects of ammonia loading (10 mmol l1 or 20 mmol l1 NH4Cl) on (A) the NH3 volatilization rate (µmol day1) and (B) the pH of the surrounding medium of Misgurnus anguillicaudatus. Open columns represent the control condition (no fish). Filled columns represent the experimental condition (with fish). Values are means + S.E.M. (N=4). *Significantly different from the corresponding control condition, P<0.05.
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Fig. 3. Effects of aerial exposure on the ammonia excretion rate (µmol day1 g1) of Misgurnus anguillicaudatus. Open columns represent the control condition. Filled columns represent the experimental condition. S, submerged; T, aerial exposure. Values are means + S.E.M. (N=4). *Significantly different from the corresponding control condition, P<0.05.
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Fig. 4. Effects of aerial exposure on the NH3 volatilization rate (µmol day1 g1) of Misgurnus anguillicaudatus. Open columns represent the control condition. Filled columns represent the experimental condition. S, submerged; T, aerial exposure. Values are means + S.E.M. (N=4). *Significantly different from the corresponding control condition, P<0.05.
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© The Company of Biologists Ltd 2002