Key result
Acute metabolic acidosis significantly increased net bicarbonate reabsorption along the loop of Henle from 133.9 to 190.2 pmol/min, demonstrating its active role in systemic acid-base regulation.
Why the study?
Do acid-base disturbances, dietary sodium, and neurohumoral factors modulate bicarbonate transport along the loop of Henle in rats?
Do acid-base disturbances, dietary sodium, and neurohumoral factors modulate bicarbonate transport along the loop of Henle in rats?
Absolute Event Rate: 190.2% vs 133.9%
p-value: p=<0.01
Bicarbonate reabsorption along the loop of Henle in vivo is closely linked to systemic acid-base status and to factors that modulate sodium transport, such as angiotensin II and renal innervation.
Rat findings extend bicarbonate regulation knowledge; leaves open human translation and clinical relevance.
The loop of Henle contributes to renal acidification by reabsorbing about 15% of filtered bicarbonate. To study the effects on loop of Henle bicarbonate transport (JHCO3) of acid-base disturbances and of several factors known to modulate sodium transport, these in vivo microperfusion studies were carried out in rats during: (a) acute and chronic metabolic acidosis, (b) acute and chronic (hypokalemic) metabolic alkalosis, (c) a control sodium diet, (d) a high-sodium diet, (e) angiotensin II (AII) intravenous infusion, (f) simultaneously intravenous infusion of both AII and the AT1 receptor antagonist DuP 753, (g) acute ipsilateral mechanicochemical renal denervation. Acute and chronic metabolic acidosis increased JHCO3; acute metabolic alkalosis significantly reduced JHCO3, whereas chronic hypokalemic alkalosis did not alter JHCO3. Bicarbonate transport increased in animals on a high-sodium intake and following AII administration, and the latter was inhibited by the AII (AT1) receptor antagonist DuP 753; acute renal denervation lowered bicarbonate transport. These data indicate that bicarbonate reabsorption along the loop of Henle in vivo is closely linked to systemic acid-base status and to several factors known to modulate sodium transport.
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Capasso et al. (1994) studied Acid-base and sodium balance disturbances (experimental) (n=77). Acute metabolic acidosis vs. Control (isotonic saline) was evaluated on Net bicarbonate transport rate (JHCO3) along the loop of Henle (p=<0.01). Acute metabolic acidosis significantly increased net bicarbonate reabsorption along the loop of Henle from 133.9 to 190.2 pmol/min, demonstrating its active role in systemic acid-base regulation.
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