- The mechanisms of regulation of H+ secretion by kidneys in acidosis have been suggested in the following statements:
A. Acidosis inhibits the secretion of cortisol by adrenal cortex
B. The transcription of Na+– H+
C. The translation of mRNA of 1Na+ – 3HCO3– symporter gene is decreased by cortisol
D. The secretion of endothelin-1(ET-1) from the proximal tubule is enhanced in acidosis
E. ET-1 stimulates the phosphorylation and subsequent insertion of the Na+– H+ antiporter into the apical membrane of proximal tubular cells
F. The insertion of 1Na+– 3HCO3– symporter into the basolateral membrane of proximal tubular cells is also increased by ET-1
Choose all CORRECT statements from the following options:
(1) A, B and C (2) B, C and D
(3) C, D and E (4) D, E and F
Kidneys play a vital role in maintaining acid-base balance by regulating H+ secretion, especially during acidosis. Several molecular and hormonal factors influence this process, ensuring acid elimination and bicarbonate conservation.
Evaluation of Proposed Statements
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A. Acidosis inhibits cortisol secretion by adrenal cortex
This is incorrect. Acidosis generally stimulates cortisol secretion which aids in renal adaptations to acid-base imbalance. -
B. The transcription of Na+-H+ exchanger (NHE3) is increased during acidosis
This is correct. Increased transcription enhances H+ secretion in proximal tubules. -
C. The translation of mRNA of 1Na+-3HCO3- symporter gene is decreased by cortisol
This is incorrect. Cortisol promotes transporter expression aiding in bicarbonate reabsorption. -
D. The secretion of endothelin-1 (ET-1) from the proximal tubule is enhanced in acidosis
This is correct; ET-1 stimulates acid secretion pathways. -
E. ET-1 stimulates phosphorylation and insertion of Na+-H+ antiporter (NHE3) into apical membrane of proximal tubular cells
This is correct; ET-1 enhances NHE3 activity/function via phosphorylation and trafficking. -
F. ET-1 also increases insertion of 1Na+-3HCO3- symporter into basolateral membrane
This is correct; ET-1 promotes bicarbonate transporter insertion at basolateral side.
Conclusion
The correct statements describing the mechanisms of H+ secretion regulation during acidosis are:
(4) D, E and F
