Reduced Na(+)-K(+)-ATPase activity and plasma lysophosphatidylcholine concentrations in diabetic patients.
A fraction from normal human plasma inhibiting Na(+)-K(+)-ATPase has been recently identified as lysophosphatidylcholine (LPC). The aim of this study was to investigate the existence of a relationship between the activity of the cellular membrane Na(+)-K(+)-ATPase and plasma LPC in human diabetes. We studied 10 patients with insulin-dependent-diabetes mellitus (IDDM), 14 patients with non-insulin-dependent diabetes mellitus (NIDDM), and 10 sex- and age-matched control subjects. Plasma LPC concentrations were increased in both IDDM and NIDDM patients compared with control subjects. Na(+)-K(+)-ATPase activity was reduced in both groups of patients in erythrocyte and platelet membranes. There was a significant correlation between the concentrations of plasma LPC and Na(+)-K(+)-ATPase activity in both erythrocyte and platelet membranes (P < 0.01). To investigate the effect of LPC on the enzyme, Na(+)-K(+)-ATPase activity was determined in erythrocyte membranes obtained from six healthy subjects after in vitro incubation with increasing concentrations of LPC (1-10 microM). Enzymatic activity was significantly reduced by in vitro LPC at a concentration of 2.5 microM, with a further decrease at 5 microM. These data suggest that the decrease in Na(+)-K(+)-ATPase activity in diabetes might be due to increased LPC concentrations.
Department of Diabetology, INRCA Hospital, Ancona, Italy.
R A
RA
Rabini
R
R
Galassi
P
P
Fumelli
N
N
Dousset
M L
ML
Solera
P
P
Valdiguie
G
G
Curatola
G
G
Ferretti
M
M
Taus
L
L
Mazzanti
D000328:Adult; D001792:Blood Platelets / Q000201:enzymology*; D015992:Body Mass Index; D002784:Cholesterol / Q000097:blood; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000201:enzymology; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000201:enzymology; D004912:Erythrocytes / Q000201:enzymology*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D008244:Lysophosphatidylcholines / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010743:Phospholipids / Q000097:blood; D012016:Reference Values; D012044:Regression Analysis; D000254:Sodium-Potassium-Exchanging ATPase / Q000097:blood*; D014280:Triglycerides / Q000097:blood
D002784:Cholesterol; D005230:Fatty Acids, Nonesterified; D006442:Glycated Hemoglobin; D008244:Lysophosphatidylcholines; D010743:Phospholipids; D000254:Sodium-Potassium-Exchanging ATPase; D014280:Triglycerides