Urea synthesis and osmotic stress in the terrestrial anurans Bufo woodhousei and Hyla cadaverina
1982; Elsevier BV; Volume: 71; Issue: 2 Linguagem: Inglês
10.1016/0300-9629(82)90402-9
ISSN0300-9629
Autores Tópico(s)Muscle metabolism and nutrition
Resumo1. Bufa woodhousei. a terrestrial toad, and Hyla cadarerina, a terrestrial treefrog, accumulate and tolerate high concentrations of urea in the body fluids during dehydration or reduced water turnover (up to 280 mM urea in B. woodhousei, 140 mM urea in H. cadaverina). 2. In contrast to Rana cancrivora. Xenopus laevis and Scaphiopus couchi (considered to be unusual in their ability to handle osmotic stress), B. woodhousei and H. cadaverina do not increase the rate of urea synthesis and therefore the rate of urea accumulation in the body fluids in response to dehydration. 3. Hepatic activity of CPS-I. the first enzyme of the urea-ornithine cycle, is correlated with a greater proportion of N waste being formed as urea rather than as NH3 during times of reduced water turnover or osmotic stress. This results in preferential accumulation of urea rather than of NH3 in the body fluids. 4. CPS-I activity is also correlated with the increased N waste production that follows from increased dietary N intake.
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