AUTHOR=Zhang Yun-Long , Wang Guang-Yi , Zhang Zi-Han , Xie Yun-Yi , Jin Hui , Dong Zhao-Ran 

TITLE=Partial Amino Acid Metabolism and Glutamine Synthesis as the Ammonia Defensive Strategies During Aerial Exposure in Chinese Loach Paramisgurnus dabryanus

JOURNAL=Frontiers in Physiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2019.00014

DOI=10.3389/fphys.2019.00014

ISSN=1664-042X

ABSTRACT=<p>The <italic>Paramisgurnus dabryanus</italic> was exposed to air to assess the changes in plasma, liver and muscle free amino acid (FAA) contents. The FAA concentrations in plasma, liver and muscle of <italic>P. dabryanus</italic> were significantly affected by aerial exposure (<italic>P</italic> &lt; 0.05). After 12 h of aerial exposure, the plasma glutamate contents increased significantly (<italic>P</italic> &lt; 0.05) and reached peak value at 24 h of air exposure. With increasing air exposure time, the plasma alanine contents increased significantly and more dramatically than the control values (<italic>P</italic> &lt; 0.05). From 24 to 48 h of aerial exposure, the liver free glutamate contents increased significantly and reached the peak value at 48 h of air exposure (<italic>P</italic> &lt; 0.05). The liver free alanine contents in air exposure group were markedly higher than these values in the control group (<italic>P</italic> &lt; 0.05). After 72 h of air exposure, the muscle free glutamate contents increased markedly (<italic>P</italic> &lt; 0.05) and were significantly higher than the control values (<italic>P</italic> &lt; 0.05). The muscle free alanine contents remained at constant values during the first 12 h of aerial exposure (<italic>P</italic> &gt; 0.05), thereafter, these concentrations increased significantly until the end of experiment (<italic>P</italic> &lt; 0.05). Our results showed that glutamate and NH<sub>4</sub><sup>+</sup> could be used to synthesize glutamine via glutamine synthetase to convert internal ammonia into non-toxic glutamine in <italic>P. dabryanus</italic> during air exposure. Furthermore, the <italic>P. dabryanus</italic> could catabolize several certain amino acids, leading alanine form to reduce endogenous ammonia production. The decrease in tissue free glutamate, arginine and proline in <italic>P. dabryanus</italic> indicated that these certain amino acids should be the starting substrate to be converted to alanine and energy.</p>