Relation of endogenous digoxin-like immunoreacting activities to salt balance and renal function in man.
We have previously shown that a natriuretic factor which is present in a small molecular weight fraction (IV) of serum and urine from salt loaded animals and healthy subjects, respectively, inhibits the Na-K-ATPase enzyme in vitro and also binds to a specific digoxin antibody. In the present study digoxin-like immunoreacting activity (DLIA) was therefore determined in the serum of healthy volunteers during low (35 nmol/day) and high (greater than 400 mmol/day) sodium intake and of patients with chronic renal failure and serum creatinine concentrations ranging from 127 to 757 mumol/l. DLIA was determined with a radioimmunoassay for digoxin in native serum and in the salt (III) and post-salt (IV) serum fractions eluted from a Sephadex G-25 column. DLIA in native serum of healthy subjects was less than 0.125 ng/ml. After gel filtration DLIA eluted exclusively in the small molecular weight salt (F III) and post-salt (F IV) fractions. Whereas DLIA increased in F III and decreased in F IV, total DLIA in F III + IV slightly increased from 0.37 +/- 0.03 to 0.49 +/- 0.05 ng/ml (p less than 0.01) with the change from low to high sodium intake. DLIA in native serum of uremic patients ranged from 0 to 1.70 ng/ml and was detectable consistently only in patients with serum creatinine concentrations above 250 mumol/l. DLIA in F III which averaged 0.22 +/- 0.04 ng/ml and total activity which ranged from 0.11 to 0.88 ng/ml closely correlated with the degree of renal impairment (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
Kramer
H J
HJ
Heppe
M
M
Pennig
J
J
Kipnowski
J
J
Klingmüller
D
D
Düsing
R
R
Krück
F
F
D000328:Adult; D000368:Aged; D002850:Chromatography, Gel; D003404:Creatinine / Q000097:blood; D004039:Diet, Sodium-Restricted; D004077:Digoxin / Q000097:blood*; D005260:Female; D006801:Humans; D007668:Kidney / Q000502:physiology*; D007676:Kidney Failure, Chronic / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011863:Radioimmunoassay; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors
D004077:Digoxin; D012964:Sodium; D003404:Creatinine; D000254:Sodium-Potassium-Exchanging ATPase