Abstract 13546: Renal Sympathetic Nerve is Involved in the Pathogenesis of Non-dipper Type Hypertension in a Rat Model of Metabolic Syndrome
Background: Although renal denervation is reported to significantly reduce blood pressure in patients with resistant hypertension, the role of renal nerve in hypertension with metabolic syndrome is unknwon. Therefore we examined the effectiveness of long-term renal denervation on SHR/NDmcr-cp(+/+) rats (SHRcp), a useful rat model of metabolic syndrome, to evaluate the role of renal nerve in hypertension with metabolic syndrome.
Method: We divided SHRcp into (1) bilateral renal denervation (RD) group and (2) sham operation group (control), to examine the effect of long-term RD on blood pressure, blood pressure circadian rhythm, metabolic disorders and organ injury. Blood pressure measurement was performed by the telemetry device after 19 weeks of RD.
Result: The findings of continuous direct blood pressure measurement with telemetry showed that SHRcp exhibited non-dipper type hypertension, indicating that SHRcp is a useful rat model for investigating impaired blood pressure circadian rhythm in metabolic syndrome. RD in SHRcp not only significantly lowered blood pressure but also improved disordered circadian rhythm of blood pressure from non-dipper type to dipper type. Moreover RD increased urinary sodium excretion and suppressed renal Na+-Cl- cotransporter (NCC) upregulation in SHRcp, indicating the natriuresis is at least partially involved in the decrease of blood pressure and the improvement of blood pressure circadian rhythm. RD significantly reduced cardiac weight, cardiac inflammation, cardiac fibrosis, coronary remodeling and vascular endothelial dysfunction, and attenuated cardiovascular oxidative stress. However, RD failed to ameliorate obesity, metabolic disorders, and renal injury in SHRcp. RD failed to reduce systemic sympathetic activity in SHRcp, though renal norepinephrine contents in SHRcp with RD were decreased to less than 10%, compared with control group (10.0±3.5 vs 114.9 ±26.7 ng/g tissue, P<0.01).
Conclusion: Our work revealed that renal sympathetic nerve is involved in the pathogenesis of non-dipper type hypertension in metabolic syndrome, via upregulation of NCC.
- © 2013 by American Heart Association, Inc.