Which statement best describes the kidney's role in acid-base balance during prolonged exercise?

Which statement best describes the kidney's role in acid-base balance during prolonged exercise?

• A. It regulates potassium balance during prolonged exercise.
• B. It increases hepatic lactate production to buffer pH.
• C. It elevates bicarbonate synthesis in plasma.
• D. It regulates bicarbonate reabsorption and hydrogen ion excretion to maintain pH during lactate-induced acidosis.

Answer: (D)

During prolonged exercise, lactate builds up and brings extra hydrogen ions into the body, pushing pH toward acidity. The kidneys counter this by two linked actions: reabsorbing bicarbonate from the filtrate so it can buffer those H+ ions, and excreting hydrogen ions in the urine. This dual approach regenerates and preserves the body's buffering capacity, helping keep blood pH within a narrow, safe range despite the acidosis caused by lactate. The detailed mechanism involves the proximal tubule reclaiming most filtered bicarbonate through a process linked to carbonic anhydrase and sodium transport, and increasing production and disposal of acidic waste forms (like ammonium and titratable acids) to remove H+ from the body. Therefore, the best description is that the kidney regulates bicarbonate reabsorption and hydrogen ion excretion to maintain pH during lactate-induced acidosis.

During prolonged exercise, lactate builds up and brings extra hydrogen ions into the body, pushing pH toward acidity. The kidneys counter this by two linked actions: reabsorbing bicarbonate from the filtrate so it can buffer those H+ ions, and excreting hydrogen ions in the urine. This dual approach regenerates and preserves the body's buffering capacity, helping keep blood pH within a narrow, safe range despite the acidosis caused by lactate.

The detailed mechanism involves the proximal tubule reclaiming most filtered bicarbonate through a process linked to carbonic anhydrase and sodium transport, and increasing production and disposal of acidic waste forms (like ammonium and titratable acids) to remove H+ from the body. Therefore, the best description is that the kidney regulates bicarbonate reabsorption and hydrogen ion excretion to maintain pH during lactate-induced acidosis.