PS-BPB04-4: RENAL DENERVATION IMPROVES THE SURVIVAL RATE VIA A REDUCTION IN HEART RATE IN HIGH SALT-FED DAHL SALT-SENSITIVE RATS. (January 2023)

• Record Type: Journal Article
• Authors: Morisawa, Norihiko; Kitada, Kento; Fujisawa, Yoshihide; Yamazaki, Daisuke; Nakano, Daisuke; Titze, Jens; Nishiyama, Akira
• Is Part Of: Journal of hypertension. Volume 41(2023)Supplement 1
• Page Start: e273
• Publication Date: 2023-01
• Subjects: Hypertension -- Periodicals; Hypertension -- Periodicals; 616.132005
• DOI: 10.1097/01.hjh.0000915516.36350.e2
• Languages: English
• ISSNs: 1473-5598

Abstract

Abstract : Objective: We reported that high salt intake decreases heart rates via a reduction in renal sympathetic activity in normal Sprague Dawley rats to compensate for high salt-driven catabolism. We also revealed that Dahl salt-sensitive (DSS) rats cannot reduce heart rates during high salt intake because of the abnormal activation of renal sympathetic nerve activity. It is known that high heart rates are negatively associated with life span. Therefore, we hypothesized that renal denervation ontributes to the long life span in high salt-fed DSS rats. Design and Method: (Experiment 1) We performed renal denervation (n = 9) or sham operation (n = 9) on male DSS rats at 4 weeks of age. At the same time, we implanted a radiotelemetry transmitter for blood pressure measurements in the above rats (sham (n = 4), renal denervation (n = 5)). After two weeks of recovery, we started feeding them a 4% NaCl diet with 0.9% NaCl water to drink (HS). We observed the survival rates, blood pressure, and heart rates. (Experiment 2) Male, 4-week-old DSS rats were divided into three groups: i) sham operation + 0.2% NaCl diet with tap water to drink, ii) sham operation + HS, and iii) renal denervation + HS (n = 6 per group). At 2 weeks post-surgery, the rats were fed the respective diets for 6 weeks. We weekly measured systolic blood pressure by a tail-cuff method. After 6 weeks of observation, we harvested their skin and skinned carcass to measure their body. Results: The renal-denervated DSS rats showed a higher survival rate compared to the sham-operated DSS rats (p < 0.05). While renal denervation showed a decrease in heart rate, there was no significant decrease in mean arterial pressure throughout the experimental period. High salt intake significantly increased body Na content (mmol/g dry weight), whereas renal denervation did not alter body Na content in DSS rats. Conclusion: Renal denervation improved the survival rate in high salt-fed Dahl salt-sensitive rats, which may be mediated by a reduction in heart rate, but not body Na content nor blood pressure.