ISSN:
1432-136X
Keywords:
Anoxia
;
ATP
;
Phosphodiester
;
Lactic acidosis
;
Turtle, Chrysemys
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Abstract Selected tissues (skeletal muscle, heart ventrical, and liver), sampled from turtles (Chrysemys picta bellii) at 3°C either under normoxic conditions or after 12 weeks of anoxic submergence were quantiaatively analysed for intracellular pH and phosphorus metabolites using 31P-NMR. Plasma was tested for osmolality and for the concentrations of lactate, calcium, and magnesium to confirm anoxic stress. We hypothesized that, in the anoxic animals, tissue ATP levels would be maintained and that the increased osmolality of the body fluids of anoxic turtles would be accounted for by a corresponding increase in the concentrations of phosphodiesters. The responses observed differed among the three tissues. In muscle, ATP was unchanged by anoxia but phosphocreatine was reduced by 80%; in heart, both ATP and phosphocreatine fell by 35–40%. The reduction in phosphocreatine in heart tissue at 3°C was similar to that observed in isolated, perfused working hearts from turtles maintained at 20°C but no decrease in ATP occurred in the latter tissues. In liver, although analyses of several specimens were confounded by line-broadening, neither ATP nor phosphocreatine was detectable in anoxic samples. Phosphosdiesters were detected in amounts sufficient to account for 30% of normoxic cell osmotic concentration in heart and 11% and 12% in liver and muscle, respectively. The phosphodiester levels did not change in anoxia. Heart ventricular phosphodiester levels in turtles at 3°C were significantly higher than those determined for whole hearts from turtles at 20°C. 1H, 13C and 31P NMR analyses of perchloric acid extracts of heart and skeletal muscle from 20°C turtles con firmed that the major phosphodiester observed by NMR in these tissues is serine ethanolamine phosphate. We conclude that the three types of tissues studied differ substantially in their ability to maintain levels of ATP during anoxia, and that liver may continue to function despite NMR-undetectable levels of this metabolite. In addition, we conclude that phosphodiesters do not serve as regulated osmolytes during anoxia, and that the functional significance of their high concentrations in turtle tissues remains uncertain.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00264689
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