Objective      To determine the effect of renal denervation on hypertension in the middle-aged rats.       Methods       A total of 25 spontaneous hypertension rats (SHR) and 25 Wistar kyoto rats (WKY) aging 30-week-old male rats

weighing 350 to 420

g were randomly divided into 5 groups randomly

that is

1-day group

4-day group

9-day group

16-day group

and 32-day group (n=10

including 5 SHR and 5 WKY rats in each group). The implementation of the renal denervation was on the second day with 10% phenol ethanol solution. Blood pressure was measured by a non-invasive tail blood pressure meter (BP-98A). The plasma and renal tissue norepinephrine (nonadrenaline

NE) content and rennin activity were detected by ELISA. The expression of α

1

- and β

1

-adrenoreceptor (α

1

-R and β

1

-R)in rat aortic smooth muscle were determined by RT-PCR and Western blotting respectively for their mRNA and protein levels.        Results      NE content and renin activity in the plasma and renal tissue were significantly higher in middle-aged SHR than in middle-aged WKY rats (P0.05). However

the expression of the aorta α

1

-R and β

1

-R at the mRNA and protein levels had no significant difference in middle-aged SHR and WKY rats (P0.05). Rapid decline in blood pressure was observed in middle-aged SHR after denervation (P0.05)

and NE content and renin activity in the plasma and renal tissue was significantly decreased (P0.05)

but the expression of the aorta α

1

-R was up-regulated (P0.05)

and β

1

-R had no difference (P0.05). In the chronic denervation period

the blood pressure as well as renal NE content and renin activity were gradually higher than normal levels (P0.05). The expression of α

1

-R and β

1

-R were up-regulated which ultimately higher than initial levels (P0.05). The expression of α

1

R and β

1

-R protein was similar with the expression of mRNA.        Conclusion      Renal denervation attenuates the high blood pressure temporarily in the middle-aged SHR. During the acute period

α

1

-R is up-regulated. However

blood pressure is gradually increased in chronic period with the up-regulation of α

1

R and β

1

-R. Changes in the b

lood pressure are consistent with the changes in the NE and renin activity.