G. Capasso et al., BICARBONATE TRANSPORT ALONG THE LOOP OF HENLE .2. EFFECTS OF ACID-BASE, DIETARY, AND NEUROHUMORAL DETERMINANTS, The Journal of clinical investigation, 94(2), 1994, pp. 830-838
The loop of Henle contributes to renal acidification by reabsorbing ab
out 15% of filtered bicarbonate. To study the effects on loop of Henle
bicarbonate transport (JHCO(3)) of acid-base disturbances and of seve
ral factors known to modulate sodium transport, these in vivo microper
fusion studies li;ere carried out in rats during: (a) acute and chroni
c metabolic acidosis, (b) acute and chronic (hypokalemic) metabolic al
kalosis, (c) a control sodium diet, (d) a high-sodium diet, (e) angiot
ensin II (AII) intravenous infusion, (f) simultaneously intravenous in
fusion of both AII and the ATI receptor antagonist DuP 753, (g) acute
ipsilateral mechanico-chemical renal denervation. Acute and chronic me
tabolic acidosis increased JHCO(3); acute metabolic alkalosis signific
antly reduced JHCO(3), whereas chronic hypokalemic alkalosis did not a
lter JHCO(3). Bicarbonate transport increased in animals on a high-sod
ium intake and following AII administration, and the latter was inhibi
ted by the AII (AT(1)) receptor antagonist DuP 753; acute renal denerv
ation lowered bicarbonate transport. These data indicate that bicarbon
ate reabsorption along the loop of Henle in vivo is closely linked to
systemic acid-base status and to several factors known to modulate sod
ium transport.