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Effect of Temperature on pH and Electrolyte Concentration in Air-Breathing Ectotherms
The Journal of Experimental Biology
  • J. N. Stinner
  • Lynn K. Hartzler, Wright State University - Main Campus
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The aim of this study was to determine the effects of temperature upon pH, protein charge and acid-base-relevant ion exchange in air-breathing ectotherms. Plasma and skeletal muscles in cane toads (Bufo marinus) and bullfrogs (Rana catesbeiana) were examined at 30, 20 and 10 °C. In addition, skeletal muscle ion concentrations were examined in black racer snakes (Coluber constrictor) at 30 and 10 °C. Cooling the amphibians produced a reduction in most of the plasma ion concentrations (Na+, K+, Ca2+, Cl-, SO42-) and in protein concentration because of increased hydration. Between 30 and 10 °C, total plasma osmolality fell by 14 % in the toads and by 5 % in the frogs. Plasma protein charge, calculated using the principle of electroneutrality, was unaffected by temperature, except possibly for the toads at 10 °C. The in vivo skeletal muscle ΔpHi/ΔT ratio, where pHi is intracellular pH and T is temperature, between 30 and 20 °C averaged −0.014 °C-1 in the toads and −0.019 °C-1 in the frogs. Between 20 and 10 °C, there was no change in pHi in the toads and a −0.005 °C-1 change in the frogs. The in vitro skeletal muscle ΔpHi/ΔT averaged −0.011 °C-1 in both toads and frogs. In all three species, skeletal muscle inulin space declined with cooling. Intracellular ion concentrations were calculated by subtracting extracellular fluid ion concentrations from whole-muscle ion concentrations. In general, temperature had a large effect upon intracellular ion concentrations (Na+, K+, Cl-) and intracellular CO2 levels. The relevance of the changes in intracellular ion concentration to skeletal muscle acid-base status and protein charge and the possible mechanisms producing the adjustments in intracellular ion concentration are discussed. It is concluded that ion-exchange mechanisms make an important contribution to adjusting pH with changes in temperature.
Citation Information
J. N. Stinner and Lynn K. Hartzler. "Effect of Temperature on pH and Electrolyte Concentration in Air-Breathing Ectotherms" The Journal of Experimental Biology Vol. 203 Iss. 13 (2000) p. 2065 - 2074 ISSN: 00220949
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