[Role of renal sympathetic nerves in renal sodium transport in ouabain-hypertensive rats].
OBJECTIVE
To investigate the role of renal sympathetic nerves in renal sodium transport in ouabain-hypertensive rats (OHR).


METHODS
Sixteen male SD rats with sham renal denervation (Sham-RDNX) and 16 with renal denervation (RDNX) were randomly into normal control group and ouabain group to receive intraperitoneal injection of normal saline (1 ml/kg) and ouabain (27.8 µg/kg) once a day, respectively. Systolic blood pressure (SBP), heart rate and body weight were recorded weekly. Food consumption of the rats was determined twice a week. After a 4-week treatment, blood and 24 h urine samples were collected to measure the serum and urinary concentration of sodium, trace lithium and creatinine. Endogenous creatinine clearance rate (Ccr), fractional excretions of sodium (FENa), fractional excretions of lithium (FELi) and fractional reabsorption of sodium in the postproximal tubules (FDRNa) were calculated. Plasma renin activity was determined by radioimmunoassay. Norepinephrine was extracted from the renal tissue and assayed for norepinephrine content by HPLC.


RESULTS
The body weight, food intake and heart rate showed no significant difference among the 4 groups (P > 0.05). After 4 weeks, the SBP of control RDNX group (CDNX) was significantly lower than that of the control Sham-DNX group (Csham)(P < 0.05); the SBP of ouabain RDNX group (ODNX) was also significantly lower than that of ouabain Sham-DNX group (Osham) (P < 0.05); RNDX lowered SBP by about 10 mmHg in both ouabain groups and control groups. The SBP was significantly higher in Osham and ODNX groups than in the corresponding control groups (P < 0.01), also significantly higher in ODNX group than in Csham group (P < 0.01). Ccr showed no significant difference among the 4 groups(P > 0.05). FENa, FELi and FDRNa were significantly lower in ouabain groups than in the corresponding control groups (P < 0.05, P < 0.01, P < 0.05), but FENa, FELi and FDRNa of ODNX group were similar with those of Osham group (P > 0.05); FENa , FELi and FDRNa were similar between CDNX and Csham groups (P > 0.05). The plasma renin activity was comparable between the 4 groups (P > 0.05). Renal norepinephrine level was markedly reduced in RDNX group compared with that in Sham-RDNX group in both ouabain and control groups (P < 0.01).


CONCLUSIONS
The increase of proximal tubule sodium reabsorption in OHR is not dependent on the renal sympathetic nerve.
Ge
Heng
H
Department of Nephrology, Second Affiliated Hospital, Xi'an Jiaotong University College of Medicine, Xi'an 710004, China. ge_heng@163.com
Jiang
Xin
X
Ren
Yan-ping
YP
Lü
Zhuo-ren
ZR
D000818:Animals; D006973:Hypertension / Q000139:chemically induced / Q000378:metabolism*; D007668:Kidney / Q000294:innervation*; D008297:Male; D010042:Ouabain; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000378:metabolism*; D015222:Sodium Channels / Q000378:metabolism; D013564:Sympathetic Nervous System / Q000502:physiology*
D015222:Sodium Channels; D010042:Ouabain; D012964:Sodium