TY - JOUR
T1 - Lithium clearance during variations in sodium intake in man
T2 - effects of sodium restriction and amiloride
AU - BOER, W. H.
AU - Koomans, H.A.
AU - MEES, E. J.DORHOUT
AU - GAILLARD, C. A.
AU - Rabelink, A.J.
N1 - M1 - 3
Boer, W H Koomans, H A Dorhout Mees, E J Gaillard, C A Rabelink, A J ENGLAND Eur J Clin Invest. 1988 Jun;18(3):279-83.
PY - 1988
Y1 - 1988
N2 - Abstract. Assuming that lithium is exclusively reabsorbed in the proximal tubules in proportion to sodium and water, the lithium clearance (CLi) has been advanced as an index of filtrate delivery from the proximal tubules. However, studies in the rat and dog showed that CLi drops sharply at fractional sodium excretion rates (FELi) below 0·4% due to lithium reabsorption in the amiloride‐sensitive segment of the distal nephron, which disqualified CLi as an index of distal filtrate delivery during sodium restriction in these animals. In order to investigate whether this phenomenon also occurs in man, we studied CLi in 103 normal subjects at varying sodium intakes, including marked sodium restriction. In contrast to findings in the rat and dog, no sharp drop but a gradual fall in CLi was observed at decreasing FENa values down to 0·02%. Maximum urine flow, another index of filtrate delivery from the proximal tubules, decreased proportionally, suggesting that the fall in CLi was due to enhanced proximal and not distal lithium reabsorption. Amiloride (15 mg p.o.) did not affect CLi despite unequivocal effects in the distal nephron in eight normal subjects at a mean FENa of 0·1%. In conclusion, a low FENa due to severe sodium restriction in man is not accompanied by strongly enhanced distal lithium reabsorption sensitive to amiloride. Thus, in contrast to the rat and dog, a low FENa forms no objection to use CLi as an index of sodium and filtrate delivery from the proximal tubules in humans. Copyright © 1988, Wiley Blackwell. All rights reserved
AB - Abstract. Assuming that lithium is exclusively reabsorbed in the proximal tubules in proportion to sodium and water, the lithium clearance (CLi) has been advanced as an index of filtrate delivery from the proximal tubules. However, studies in the rat and dog showed that CLi drops sharply at fractional sodium excretion rates (FELi) below 0·4% due to lithium reabsorption in the amiloride‐sensitive segment of the distal nephron, which disqualified CLi as an index of distal filtrate delivery during sodium restriction in these animals. In order to investigate whether this phenomenon also occurs in man, we studied CLi in 103 normal subjects at varying sodium intakes, including marked sodium restriction. In contrast to findings in the rat and dog, no sharp drop but a gradual fall in CLi was observed at decreasing FENa values down to 0·02%. Maximum urine flow, another index of filtrate delivery from the proximal tubules, decreased proportionally, suggesting that the fall in CLi was due to enhanced proximal and not distal lithium reabsorption. Amiloride (15 mg p.o.) did not affect CLi despite unequivocal effects in the distal nephron in eight normal subjects at a mean FENa of 0·1%. In conclusion, a low FENa due to severe sodium restriction in man is not accompanied by strongly enhanced distal lithium reabsorption sensitive to amiloride. Thus, in contrast to the rat and dog, a low FENa forms no objection to use CLi as an index of sodium and filtrate delivery from the proximal tubules in humans. Copyright © 1988, Wiley Blackwell. All rights reserved
KW - Amiloride/pharmacology Diet, Sodium-Restricted Diuresis/drug effects Electrolytes/urine Female Hemodynamics/drug effects Humans Hydrogen-Ion Concentration Lithium/pharmacokinetics Male Phosphates/urine Uric Acid/urine
UR - https://www.scopus.com/pages/publications/0023920515
U2 - 10.1111/j.1365-2362.1988.tb01259.x
DO - 10.1111/j.1365-2362.1988.tb01259.x
M3 - Article
C2 - 3138131
SN - 0014-2972
VL - 18
SP - 279
EP - 283
JO - European Journal of Clinical Investigation
JF - European Journal of Clinical Investigation
IS - 3
ER -