• Diurnal variation in renal and extra-renal excretion of ammonia-N and urea-N in a freshwater air-breathing teleost,Heteropneustes fossilis (Bloch)

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    • Keywords


      Diurnal variation; nitrogen excretion; renal and extra-renal excretion; ammonia-N; urea-N; freshwater air-breathing teleost

    • Abstract


      Diurnal pattern of excretion of ammonia-N and urea-N through the renal and extra-renal sources were studied in a freshwater air-breathing teleost,Heteropneustes fossilis in its aquatic medium. Ammonia-N was the major nitrogen excretory product, however, the rate of excretion of urea-N was comparatively higher than other freshwater teleosts. Almost all ammonia-N (>99%) and about 75% of urea-N were excreted through the extra-renal sources. The excretion rate of urea-N was about 10 times higher than ammonia-N through the renal and ammonia-N was 7–8 times higher than urea-N through extra-renal sources. Existence of a functional ornithine-urea cycle reported inHeteropneustes fossilis has been suggested to be the reason for this increased rate of urea excretion.

      Nitrogen excretion (total ammonia-N + urea-N) during the night was significantly higher than the day. A higher rate of nitrogen metabolism at night has been suggested forHeteropneustes fossilis which has been reported to be nocturnal in habit.

    • Author Affiliations


      N Saha1 J Chakravorty1 B K Ratha1

      1. Biochemical Adaptation Laboratory, Department of Zoology, North-Eastern Hill University, Shillong - 793 014, India
    • Dates


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