EFFECT OF CASEIN-BASED SEMISYNTHETIC FOOD ON RENAL ACID EXCRETION ANDACID-BASE STATE OF BLOOD IN DOGS

Urinary acid excretion and blood acid-base stare were determined in do gs fed a casein-based semi-synthetic food (SSF), to which different am ounts of salts had been added, in comparison with feeding normal dog f ood. Net acid excretion (NAE) and inorganic acid excretion (IAE) incre ased during SSF feeding. IAE was higher than the acid load calculated from the sulphur and phosphorus content of the casein. This higher IAE appeared to be due to the presence of calcium and magnesium phosphate in the diet, because calcium and magnesium may be in part precipitate d as carbonate, leaving phosphate to be absorbed as phosphoric acid. A cid excretion decreased by addition of CaO. When no neutral Na+ and K salts were added, the increase in NAE was accompanied by a metabolic acidosis. K+ was more effective in attenuating the acidosis than Na+. On the basis of these findings a diet can be made which imposes a know n acid load, and provides stable baseline values. Hence, any additions that influence the acid-base balance can be properly studied. The dat a obtained in these and future studies utilising this diet may be of h elp in optimising the composition of nutrient solutions to be used in the care of critically ill patients.