Intracellular and extracellular acid-base and electrolyte status of submerged anoxic turtles at 3 degrees C.

Specimens of fresh water turtles (Chrysemys picta bellii) were acclimated to 3 degrees C and then submerged in completely anoxic water for time periods of up to 12 weeks. Blood withdrawn via indwelling arterial catheters was analysed for plasma pH, PCO2, bicarbonate concentration, [lactate], [Na+], [K+], [Ca2+] and [Mg2+], and tissue samples of skeletal muscle, liver and cardiac muscle were excised. Samples of skeletal muscle were analysed for intracellular pH (DMO), [lactate], [Na+], [K+], [Ca2+], and [Mg2+], and samples of liver and cardiac muscle for intracellular pH and [lactate] during normoxia and after 1, 2, 4, 8 and 12 weeks of anoxia. Arterial plasma pH fell from 8.0 during normoxia to lower than 7.2 concomitant with a reduction in plasma [HCO3-] after 12 weeks of anoxia due to the production of large amounts of lactic acid. The intracellular pH (pHi) of heart muscle and liver dropped in parallel or even more than plasma pH, whereas pHi in skeletal muscle changed less resulting in a delta pHi/delta pHe value of less than 0.6. Intracellular [lactate] and [Ca2+] increased considerably, but attained concentrations much smaller than those observed in the extracellular compartment. The intracellular concentrations of K+, Na+ and Mg2+ were also significantly affected, the changes, however, were small in comparison with those observed for Ca2+ and lactate concentration. The water distribution between intra- and extracellular compartments remained essentially unaffected by anoxia. It is concluded that the considerable increase in extracellular Mg2+ and Ca2+ cannot be the result of release from muscle cells and has to be attributed to release from skeleton and shell.(ABSTRACT TRUNCATED AT 250 WORDS)