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

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Abstract
Changes in the excretion of bicarbonate, sodium and potassium in one kidney after exclusion (complete sudden ligation of renal pedicle) of its partner have been studied in 16 dogs undergoing bicarbonate diuresis. Fluid balance, haematocrit, plasma electrolyte and protein concentrations were maintained constant throughout the experiment. Acute contralateral renal pedicle ligation lead to an immediate increase in bicarbonate as well as water, sodium and potassium excretion by the remaining kidney. The rapid and immediate increase in the fractional and absolute rates of bicarbonate excretion was observed at varying levels of bicarbonate loading, with the greatest response occurring at the highest infusion rate. Sodium, potassium and water excretion also increased in parallel with urinary bicarbonate loss. The increase in bicarbonate 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 sodium and bicarbonate excretion occurred despite similar continued infusion of sodium bicarbonate. It was concluded that exclusion of one kidney induces immediate adaptive excretory changes for sodium and bicarbonate in the remaining kidney, and that these changes are not accounted for by any of the known factors normally regulating sodium and bicarbonate excretion.