Abnormalities of sodium transport in non-insulin-dependent diabetes: association with renal disease.
We investigated both sodium-lithium countertransport (Na-Li CT) and ouabain-sensitive sodium transport (Na pump) of erythrocytes in healthy subjects (group A), patients with non-insulin-dependent diabetes (NIDDM) without nephropathy (group B), patients in the proteinuric stage (group C), and those in the renal insufficiency stage (group D). Erythrocytes from all four groups had a similar initial water and ionic content and were loaded with similar degrees of Li and Na for efflux studies. There were no significant differences in erythrocyte Na-Li CT or Na pump among the four groups. However, the maximal rate of Na-Li CT was significantly higher in a group of subjects with essential hypertension when compared with groups A, B and C, consistent with the view that there is a genetic marker for essential hypertension. Ouabain-insensitive Na efflux (Na leak) of erythrocytes was found to be significantly higher in group D than in groups A or B. Also, a significant positive correlation existed between Na leak and urine protein levels of the subjects studied. Our results thus indicate that in contrast with insulin-dependent diabetic patients (IDDM) where an elevated Na-Li CT is observed, with diabetic nephropathy, Na-Li CT in NIDDM is apparently not associated with nephropathy; rather the ouabain-insensitive Na efflux appears to be correlated with the stages of nephropathy in NIDDM. The association suggests that the rate of ouabain-insensitive Na efflux may provide an index for assessing the degree of nephropathy in NIDDM patients.
Lau
Y T
YT
Department of Physiology, Chang Gung Medical College, Tao-Yuan, Taiwan, R.O.C.
Huang
H S
HS
Shi
F C
FC
Fan
M C
MC
Lin
J D
JD
Juang
J H
JH
Chen
J Y
JY
Huang
M J
MJ
Chen
M C
MC
D000328:Adult; D000368:Aged; D017920:Antiporters / Q000502:physiology*; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism*; D003928:Diabetic Nephropathies / Q000378:metabolism*; D005260:Female; D006801:Humans; D017136:Ion Transport; D008297:Male; D008875:Middle Aged; D012964:Sodium / Q000378:metabolism*
D017920:Antiporters; C045885:sodium-lithium countertransporter; D012964:Sodium