THE EFFECT OF PROLONGED ANOXIA AT 3-DEGREES-C ON TISSUE HIGH-ENERGY PHOSPHATES AND PHOSPHODIESTERS IN TURTLES - A P-31 NMR-STUDY

Selected tissues (skeletal muscle, heart ventrical, and liver), sample d from turtles (Chrysemys picta bellii) at 3 degrees C either under no rmoxic conditions or after 12 weeks of anoxic submergence were quantit atively analysed for intracellular pH and phosphorus metabolites using P-31-NMR. Plasma was tested for osmolality and for the concentrations of lactate, calcium, and magnesium to confirm anoxic stress. We hypot hesized that, in the anoxic animals, tissue ATP levels would be mainta ined and that the increased osmolality of the body fluids of anoxic tu rtles would be accounted for by a corresponding increase in the concen trations of phosphodiesters. The responses observed differed among the three tissues. In muscle, ATP was unchanged by anoxia but phosphocrea tine was reduced by 80%; in heart, both ATP and phosphocreatine fell b y 35-40%. The reduction in phosphocreatine in heart tissue at 3 degree s C was similar to that observed in isolated, perfused working hearts from turtles maintained at 20 degrees C but no decrease in ATP occurre d in the latter tissues. In liver, although analyses of several specim ens were confounded by line-broadening, neither ATP nor phosphocreatin e was detectable in anoxic samples. Phosphosdiesters were detected in amounts sufficient to account for 30% of normoxic cell osmotic concent ration in heart and 11% and 12% in liver and muscle, respectively. The phosphodiester levels did not change in anoxia. Heart ventricular pho sphodiester levels in turtles at 3 degrees C were significantly higher than those determined for whole hearts from turtles at 20 degrees C. H-1, C-13 and P-31 NMR analyses of perchloric acid extracts of heart a nd skeletal muscle from 20 degrees C turtles con firmed that the major phosphodiester observed by NMR in these tissues is serine ethanolamin e phosphate. We conclude that the three types of tissues studied diffe r substantially in their ability to maintain levels of ATP during anox ia, and that liver may continue to function despite NMR-undetectable l evels of this metabolite. In addition; we conclude that phosphodiester s do not serve as regulated osmolytes during anoxia, and that the func tional significance of their high concentrations in turtle tissues rem ains uncertain.