Related Experiment Video
Updated: Jun 22, 2026

Culturing Primary Rat Inner Medullary Collecting Duct Cells
Published on: June 21, 2013
Bicarbonate secretion and chloride absorption by rabbit cortical collecting ducts. Role of chloride/bicarbonate
Abstract:
Cortical collecting ducts (CCD) from rabbits treated with deoxycorticosterone (DOC) actively secrete bicarbonate at high rates. To investigate the mechanism of bicarbonate secretion, we measured bicarbonate and chloride transport in CCD from rabbits treated with DOC for 9-24 d. Removal of chloride (replaced with gluconate) from both perfusate and bath inhibited bicarbonate secretion without changing transepithelial voltage. Removal of chloride only from the bath increased bicarbonate secretion, while removal of chloride only from the perfusate inhibited secretion. In contrast to the effect of removing chloride, removal of sodium from both the perfusate and bath (replacement with N-methyl-D-glucamine) did not change the rate of bicarbonate secretion. The rate of bicarbonate secretion equaled the rate of chloride absorption in tubules bathed with 0.1 mM ouabain to inhibit any cation-dependent chloride transport. Under these conditions, chloride absorption occurred against an electrochemical gradient. Removal of bicarbonate from both the perfusate and bath inhibited chloride absorption. Removal of bicarbonate only from the bath inhibited chloride absorption, while removal of bicarbonate from the lumen stimulated chloride absorption. We conclude that CCD from DOC-treated rabbits actively secrete bicarbonate and actively absorb chloride by an electroneutral mechanism involving 1:1 chloride/bicarbonate exchange. The process is independent of sodium.
More Related Videos
Related Concept Videos
Reabsorption and Secretion in the PCT
Transport mechanisms involving sodium ions (Na+) contribute significantly to solute reabsorption. These mechanisms include symport and antiport processes.
A key example is the...
Reabsorption and Secretion in the Loop of Henle
Reabsorption and Secretion in the DCT and Collecting Duct
The distal part of the DCT, along with the...
Roles of Electrolytes: Chloride and Bicarbonate
Conditions such as hypochloremia can arise from insufficient chloride reabsorption by the kidneys, often compounded by extended bouts of diarrhea, vomiting, or...
Renal Regulation of Acid-Base Balance
In the kidneys, cells within the proximal convoluted tubules (PCT) and the collecting ducts secrete hydrogen ions (H+) into the tubular fluid. Specifically, in the PCT, Na+/H+ antiporters secrete H+ while reabsorbing Na+.
However, the intercalated cells in...
Physiology of the Genitourinary System II: Tubular Reabsorption and Secretion

