Skeletal carbon dioxide stores during metabolic acidosis

These experiments were performed to examine the buffering functions of skeletal carbon dioxide during metabolic acidosis. Acidosis of several days duration was produced in rats either by inclusion of acidogenic substances in the diet or by chemical induction of diabetic ketoacidosis. Titrimetric methods were used to measure the carbon dioxide content of bone, which was divided into readily exchangeable and slowly exchangeable pools according to a model described in the text. Acid feeding resulted in a mild acidemia (blood pH greater than 7.25), whereas profound metabolic acidemia occurred during diabetic ketoacidosis (blood pH less than 7.00). Total bone carbon dioxide was reduced during both forms of metabolic acidosis. This reduction in skeletal carbon dioxide occurred within the first 24 h after the onset of metabolic acidosis, was associated with a decline in the readily exchangeable fraction of skeletal carbon dioxide, and was directly proportional to the declines in extracellular bicarbonate concentration and plasma carbon dioxide tension.