Acid-base changes in milk and blood of rats in acidosis and alkalosis

Lactating white rats (Rattus norvegicus) were subjected to metabolic and respiratory acidosis and metabolic alkalosis. Before and during the various treatments, the acid-base status of heart blood and milk was determined. Acute metabolic acidosis lowered the pH of plasma and milk; Pco(2) and bicarbonate concentrations in plasma were lowered, and in milk Pco(2) was raised and the bicarbonate concentration remained unchanged. Respiratory acidosis and acetazolamide caused a drop in blood pH and in blood and milk bicarbonate concentrations; milk pH remained unchanged, but Pco(2) was raised in both plasma and milk. Acute metabolic alkalosis raised the blood pH and milk Pco(2); plasma Pco(2) and bicarbonate concentrations in blood and milk remained unchanged. The data show that greater changes occur in acid-base parameters of blood than milk when animals are exposed to acidifying and alkalinizing stimuli.