[The change of human Na+/dicarboxylate co-transporter 1 expression in the kidney and its relationship with pathogenesis of nephrolithiasis].
OBJECTIVE
To study the change of Na+/dicarboxylate co-transporter 1 expression in the kidney and its relationship with nephrolithiasis.


METHODS
50 volunteers and 85 patients with nephrolithiasis were divided into 3 groups: control, nephrolithiasis with normal urine citrate, and nephrolithiasis with hypocitraturia. The expression of hNaDC1 mRNA in kidney was determined by RT-PCR or Northern blotting, the change of hNaDC1 protein abundance were measured by immunohistochemical staining with anti-hNaDC1 antibody among part of these patients and volunteers. The plasma and urinary biochemical parameters, such as citrate, oxalate, uric acid and calcium etc., were analyzed by routine chemical methods.


RESULTS
The recurrence rate of nephrolithiasis in the group of patients with hypocitraturia was 36.1%, significantly higher than the recurrence rate of 16.3% in the group of patients with normal urine citrate (P < 0.01). hNaDC1 was expressed in the normal kidney, localized in the striated border of renal proximal tubule. However, it was expressed highly in the kidneys of patients with hypocitraturia. The ratio hNaDC1 mRNA/18sRNA in the patients with hypocitraturia was 0.65 +/- 0.21, significantly higher than that in the controls (0.36 +/- 0.11, P < 0.01). The ratio hNaDC1 mRNA/18sRNA in the patients with normal urine citrate was not significantly different from that in the controls (P > 0.05). The urine pH and urine sodium were significantly lower in the patients with hypocitraturia than in the other two groups. The levels of urine calcium and urine oxalate were significantly higher in the patients with hypocitraturia than in the controls, and were not different from those in the patients with normal urine citrate.


CONCLUSIONS
The upregulation of hNaDC1 mRNA and protein abundance in the kidney may be an important cause of hypocitraturia, which might be related with the occurrence and recurrence of nephrolithiasis.
He
Y
Y
Division of Nephrology, Kidney Center and Key Lab of PLA, General Hospital of PLA, Beijing 100853, China.
Chen
X
X
Yu
Z
Z
D000328:Adult; D015152:Blotting, Northern; D029382:Dicarboxylic Acid Transporters / Q000032:analysis / Q000235:genetics*; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D007150:Immunohistochemistry; D007668:Kidney / Q000378:metabolism*; D007669:Kidney Calculi / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D029363:Organic Anion Transporters, Sodium-Dependent / Q000032:analysis / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D027981:Symporters / Q000032:analysis / Q000235:genetics*
D029382:Dicarboxylic Acid Transporters; D029363:Organic Anion Transporters, Sodium-Dependent; D012333:RNA, Messenger; C092524:SLC13A2 protein, human; D027981:Symporters