[Effect of temperature increase on some aspects of nitrogen catabolism in rainbow trout (Salmo gairdneri Rich.)].

Rainbow trout acclimatized to 9 degrees C were subjected to a temperature increase (up to 17 degrees C) for 16 hrs. During the period of acclimatization to 17 degrees C, we studied blood ammonia and urea and the hepatic activity of glutamate dehydrogenase, glutaminase, uricase and arginase. The daily mean rates of blood ammonia and urea did not differ significantly at 9 and 17 degrees C. However, the pattern of these two parameters during the circadian cycle was not the same at 9 degrees C as after 23 days at 17 degrees C. The enzymatic activities rose after one day at 17 degrees C and remained unchanged, except for arginase which showed perfect thermal compensation. During the circadian cycle, there was some similitude between glutaminase activity and blood ammonia at 9 degrees C and after 23 days at 17 degrees C, as well as between arginase activity and blood urea.