Compensatory Adaptation of Bicarbonate Excretion Following Acute Contralateral Kidney Exclusion in the Dog

Abstract

Changes in the excretion of HCO3, Na and K in 1 kidney after exclusion (complete sudden ligation of renal pedicle) of its partner were studied in 16 dogs undergoing HCO3 diuresis. Fluid balance, hematocrit, plasma electrolyte and protein concentrations were maintained constant throughout the experiment. Acute contralateral renal pedicle ligation lead to an immediate increase in HCO3, water, Na and K excretion by the remaining kidney. The rapid and immediate increase in the fractional and absolute rates of HCO3 excretion was observed at varying levels of HCO3 loading, with the greatest response occurring at the highest infusion rate. Na, K and water excretion also increased in parallel with urinary HCO3 loss. The increase in HCO3 excretion was not accounted for by changes in extracellular fluid volume, plasma composition, glomerular filtration rate, effective renal plasma flow, aldosterone and vasopressin. In 8 sham-operated animals, no abrupt increase in Na and HCO3 excretion occurred despite similar continued infusion of NaHCO3. Exclusion of 1 kidney induced immediate adaptive excretory changes for Na and HCO3 in the remaining kidney. These changes were not accounted for by any of the known factors normally regulating Na and HCO3 excretion.