[Na+/dicarboxylate cotransporter expression changed with aging in basolateral membrane of the renal tubular epithelial cells].
OBJECTIVE
To study the change with aging of Na(+)/dicarboxylate cotransporter (NaDC3) expression in basolateral membrane of epithelial cell in proximal renal tubules in rat and human being.


METHODS
Six groups of 6 Wistar rats at the age of: 1 day, 7 days, 1 month, 3 months, 12 months, and 24 months respectively were killed and their kidneys were taken to be examined immunohistochemically. Samples of kidney from 15 normal human beings, 5 in the group aged 6 - 8, 5 in the group aged 32 - 44, and 5 in the group aged 63 - 65, were examined immunohistochemically. Northern blotting, and Western blotting were used to detect the mRNA and protein expression of NaDC3 in renal tissues from both rats and human beings. The concentrations of citrate in both plasma and urine of the rats were tested.


RESULTS
(1) The concentration of citrate in urine was340 mg/L +/- 144 mg/L in rats at the age of 7 days and declined gradually with aging significantly to the value of 59 mg/L +/- 27 mg/L in the rats aged 24 months (P < 0.05). The concentration of citrate in rat plasma was 85 mg/L +/- 45 mg/L and then declined gradually with aging significantly to the value of 31 mg/L +/- 20 mg/L at the age of 24 months (P < 0.05). (2) The renal expression of both mRNA and protein of NaDC3 increased with aging in rats and human beings (P < 0.01). (3) Located in the basolateral membrane of epithelial cell in the proximal renal tubule, NaDC3 expression began to be detected in rat since at the age of 7 days and then increased gradually in comparison with that at the day 7 (P < 0.01). However, the value of NaDC3 expression at the age of 24 months was not significantly different from that at the age of 12 months (P > 0.05). Similar results were also observed in normal human beings.


CONCLUSIONS
NaDC3 may play a role in the aging process through the metabolic mechanism of citrate, etc.
Peng
Li-xia
LX
Department of Nephrology, Kidney Center and Key Lab of People's Liberation Army, General Hospital of People's Liberation Army, Beijing 100853, China.
Chen
Xiang-mei
XM
Liu
Hang
H
Hong
Quan
Q
Zhang
Li
L
Shi
Suo-zhu
SZ
Zhang
Xue-guang
XG
Bai
Xue-yuan
XY
Zhu
Han-yu
HY
D000328:Adult; D000368:Aged; D000375:Aging / Q000378:metabolism*; D000818:Animals; D002648:Child; D029382:Dicarboxylic Acid Transporters / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007687:Kidney Tubules, Proximal / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008875:Middle Aged; D029363:Organic Anion Transporters, Sodium-Dependent / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D027981:Symporters / Q000378:metabolism*
D029382:Dicarboxylic Acid Transporters; D008565:Membrane Proteins; D029363:Organic Anion Transporters, Sodium-Dependent; D027981:Symporters