Evidence of a dynamic aldosterone-independent distal tubular control of renal sodium excretion in compensated liver cirrhosis.
OBJECTIVE
In preascitic cirrhosis increased sodium retention occurs in kidney distal tubule in spite of normal aldosterone plasma levels. No clearance technique can dissect the respective contribution to sodium retention exerted by Henle's loop, distal convoluted tubule and collecting duct, so we evaluated proximal and distal tubular sodium handling in preascites during two manoeuvres that temporarily increase aldosterone secretion.


METHODS
Ten patients with compensated cirrhosis and nine controls were studied in recumbency, during standing and after dopamine receptor blockade with metoclopramide through: 4 h renal clearances of sodium, potassium, lithium and creatinine; plasma levels of active renin and aldosterone.


RESULTS
Whilst comparable in recumbency, aldosterone levels significantly rose during standing and after metoclopramide in both groups. In patients, dopaminergic blockade caused a fall of distal sodium delivery (P < 0.01) but urinary sodium excretion was unchanged because the reabsorbed fraction of distal sodium delivery also fell (P < 0.03). Cirrhotic patients showed the same findings in the passage from recumbency to standing.


CONCLUSIONS
In preascitic cirrhosis, the distal tubular segments of the nephron are able to cope with decreases in tubular flow by reducing reabsorption at an aldosterone-independent site (possibly the loop of Henle).
Sansoè
G
G
Gastroenterology Division, Gradenigo Hospital, 10153 Turin, Italy. giovannisan@iol.it
Silvano
S
S
Rosina
F
F
Smedile
A
A
Rizzetto
M
M
D000328:Adult; D000368:Aged; D000450:Aldosterone / Q000097:blood / Q000502:physiology*; D018492:Dopamine Antagonists / Q000494:pharmacology; D005260:Female; D006801:Humans; D007668:Kidney / Q000503:physiopathology; D007686:Kidney Tubules, Distal / Q000187:drug effects / Q000378:metabolism*; D008094:Lithium / Q000378:metabolism; D008103:Liver Cirrhosis / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D008787:Metoclopramide / Q000494:pharmacology; D008875:Middle Aged; D009318:Natriuresis / Q000187:drug effects; D011187:Posture; D012083:Renin / Q000097:blood; D012964:Sodium / Q000378:metabolism*; D016683:Supine Position
D018492:Dopamine Antagonists; D000450:Aldosterone; D008094:Lithium; D012964:Sodium; D012083:Renin; D008787:Metoclopramide