Na+, K(+)-ATPase inhibitory activity of fractionated urine during changes in dietary sodium intake in man.
Na+, K(+)-ATPase inhibitory activity in urine fractionated by HPLC was quantified in 7 normotensive male subjects during changes in dietary sodium intake. Subjects were studied on free sodium intake for 2 days, on low sodium intake (2 g/day) for 3 days, on high sodium intake (22 g/day) for 4 days and subsequently on normal sodium intake (6 g/day) for 2 days. Na+, K(+)-ATPase inhibitory activity in fraction 10 eluted with 17% acetonitrile by reverse-phase HPLC was 12.3 +/- 5.2% (mean +/- S.D.) on free sodium intake, 8.7 +/- 9.8% on the 3rd day of low sodium intake, 61.2 +/- 6.6% on the 4th day of high sodium intake, and 20.5% +/- 0.7% on the 2nd day of the normal sodium intake. Changes in Na+, K(+)-ATPase inhibitory activity of fraction 10 were closely associated with those in urinary sodium excretion. These results suggest that an endogenous Na+, K(+)-ATPase inhibitor(s) which plays a physiological role in the control of sodium and water balance may exist in this particular fraction.
Imafuku
T
T
Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan.
Ogawa
Z
Z
Itoh
H
H
Suzuki
H
H
Saruta
T
T
D000328:Adult; D002851:Chromatography, High Pressure Liquid; D004077:Digoxin / Q000032:analysis; D005230:Fatty Acids, Nonesterified / Q000032:analysis; D006801:Humans; D008297:Male; D010743:Phospholipids / Q000032:analysis; D014176:Protein Biosynthesis; D011506:Proteins; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors*; D012982:Sodium, Dietary / Q000494:pharmacology*; D000097795:ATPase Inhibitory Protein
D004077:Digoxin; D005230:Fatty Acids, Nonesterified; D010743:Phospholipids; D011506:Proteins; D006180:Proton-Translocating ATPases; D012982:Sodium, Dietary; D000097795:ATPase Inhibitory Protein