Maintenance of high extracellular pH does not influence cell pH or metabolism in submerged anoxic bullfrogs

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Abstract
We compared extracellular and intracellular acid‐base states in paralyzed bullfrogs subjected to 4 h of anoxic submergence at 15°C with or without maintenance of extracellular pH at preanoxic levels by bicarbonate infusion. We also assessed anaerobic metabolism under these conditions by measuring tissue lactate and glycogen concentrations in liver, heart, and skeletal muscle. Although bicarbonate infusion resulted in a significantly higher arterial blood pH (pHe) than saline infusion, intracellular pH (pHi) of heart and skeletal muscle, as determined by the DMO equilibration technqiue, were not significantly different after 4 h of anoxia. We were also unable to demonstrate any differences in anaerobic metabolic rate, since both tissue lactate accumulation and glycogen depletion were identical in bicarbonate‐ and saline‐infused frogs in the tissues studied. We conclude that (1) alterations in the extracellular acid‐base state by bicarbonate infusion are not necessarily reflected in the intracellular compartment, perhaps due to powerful intracellular buffering processes, and (2) maintenance of an alkaline extracellular pH during anoxia in bullfrogs does not influence the anaerobic metabolic rate. We could not, however, rule out a possible role for intracellular pH in regulating anaerobic metabolism during anoxia in frogs.