NTPDase and acetylcholinesterase activities in silver catfish, Rhamdia quelen (Quoy & Gaimard, 1824) (Heptapteridae) exposed to interaction of oxygen and ammonia levels

作者：Kaizer Rosilene Rodrigues^*; Loro Vania Lucia; Chitolina Schetinger Maria Rosa; Morsch Vera Maria; Tabaldi Luciane Almeri; da Rosa Cintia Saydelles; Garcia Luciano de Oliveira; Becker Alexssandro G; Baldisserotto Bernardo

来源：Neotropical Ichthyology, 2009, 7(4): 635-640.

DOI：10.1590/s1679-62252009000400012

• Fish
• ATP
• ADP
• AChE

The effects of various levels of oxygen saturation and ammonia concentration on NTPDase (ecto-nucleoside triphosphate diphosphohydrolase, E. C. 3.6.1.5) and acetylcholinesterase (AChE, E. C. 3.1.1.7) activities in whole brain of teleost fish (Rhamdia quelen) were investigated. The fish were exposed to one of two different dissolved oxygen levels, including high oxygen (6.5 mg.L(-1)) or low oxygen (3.5 mg.L(-1)), and one of two different ammonia levels, including high ammonia (0.1 mg.L(-1)) or low ammonia (0.03 mg.L(-1)) levels. The four experimental groups included the following (A) control, or high dissolved oxygen plus low NH(3); (B) low dissolved oxygen plus low NH(3); (C) high dissolved oxygen plus high NH(3); (D) low dissolved oxygen plus high NH(3). We found that enzyme activities were altered after 24 h exposure in groups C and D. ATP and ADP hydrolysis in whole brain of fish was enhanced in group D after 24 h exposure by 100% and 119%, respectively, compared to the control group. After 24 h exposure, AChE activity presented an increase of 34% and 39% in groups C and D, respectively, when compared to the control group. These results are consistent with the hypothesis that low oxygen levels increase ammonia toxicity. Moreover, the hypoxic events may increase blood flow by hypoxia increasing NTPDase activity, thus producing adenosine, a potent vasodilator.

• 出版日期2009-12-18