Lipids as endogenous Na,K-ATPase inhibitors in plasma of healthy individuals and in dialysis dependent patients.
We assayed plasma Na,K-ATPase inhibitory activity due to total lipids and lipid fractions. The effect of dialysis on the Na,K-ATPase inhibitory activity was also studied. Plasma lipid extracts from 11 healthy volunteers and 9 dialysis-dependent patients (pre and post dialysis) were separated into neutral lipids and phospholipids. Further fractionation was by thin layer chromatography. These lipid fractions were analyzed for Na,K-ATPase inhibitory activity by displacement of [3H]-ouabain from hog brain Na,K-ATPase. Total inhibitory activity was significantly increased (p less than 0.001) in the post-dialysis plasma compared to pre-dialysis plasma of the same patient group and to controls (482, 85 and 78 nmol/L respectively; means of the groups in digoxin equivalents). The major inhibitory activity was associated with non-esterified fatty acids with modest contributions from four other lipid fractions. Our results show that endogenous lipids are major plasma Na,K-ATPase inhibitors in vitro under these assay conditions.
Vasdev
S C
SC
Memorial University of Newfoundland, Canada.
Longerich
L
L
Prabhakaran
V M
VM
Triggle
C R
CR
Gault
M H
MH
D000328:Adult; D002855:Chromatography, Thin Layer; D003956:Dialysis; D004077:Digoxin / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000378:metabolism*; D005260:Female; D006801:Humans; D050356:Lipid Metabolism; D008297:Male; D008875:Middle Aged; D010042:Ouabain / Q000378:metabolism; D011863:Radioimmunoassay; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors* / Q000097:blood
D005230:Fatty Acids, Nonesterified; D010042:Ouabain; D004077:Digoxin; D000254:Sodium-Potassium-Exchanging ATPase