TISSUE ACID-BASE BALANCE IN ACETAZOLAMIDE-TREATED RATS

¹ Department of Pharmacology, University of Utah College of Medicine, Salt Lake City, Utah

Extracellular and intracellular acid-base parameters were measured in intact and nephrectomized rats treated with acetazolamide. Tissue cell pH values in muscle and brain were determined from both the distribution of CO₂ and 5,5-dimethyloxazolidine-2,4-dione. It was found that acetazolamide produced a noncarbonic acidosis in intact animals, but caused a carbonic acid acidosis in nephrectomized animals. Despite the fall in extracellular pH caused by acetazolamide in intact animals, brain intracellular pH tended to rise. Muscle cell pH values did not change significantly in acetazolamide-treated intact or nephrectomized animals. The CO₂ and 5,5-dimethyloxazolidine-2,4-dione methods gave qualitatively similar results in all experiments. It was concluded that the apparently small effect of acetazolamide on brain intracellular pH cannot be simply explained but may be a consequence of several factors including possible errors in the 5,5-dimethyloxazolidine-2,4-dione method when applied to brain intracellular acid-base studies after acetazolamide administration.