2015 Fiscal Year Annual Research Report
Chronic electrical activation of the arterial baroreflex in hypertensive rats - determining the role of unmyelinated baroreceptors
| Project/Area Number |
26750153
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| Research Institution | National Cardiovascular Center Research Institute |
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Principal Investigator |
TURNER MICHAEL 国立研究開発法人国立循環器病研究センター, 研究所, 流動研究員 (90714204)
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| Project Period (FY) |
2014-04-01 – 2016-03-31
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| Keywords | Baroreflex / Hypertension / Resiniferatoxin / Capsaicin / Nerve Stimulation |
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| Outline of Annual Research Achievements |
Baroreflex activation therapy (BAT) is a device-dependent therapy for hypertension, which utilizes the electrical stimulation of baroreceptors. There are two types of baroreceptors: myelinated (A-fiber) and unmyelinated (C-fiber). The electrical stimulation of either A-fiber or C-fiber baroreceptors may have significantly different outcomes in patients. We hypothesized that the central processing of A-fiber and C-fibers are affected differently during the development of hypertension and BAT. To understand the role of both types of baroreceptors we investigated both dynamic short-term stimulation and long-term stimulation of the aortic depressor nerve. Using dynamic short-term stimulation, we have identified that the central processing of A-fiber and C-fiber central pathways are significantly different. A-fiber central pathways exhibit derivative characteristic (gain increases with stimulation frequency), whereas, C-fiber central pathways show non-derivative characteristics (gain is consistent at all stimulation frequencies). In spontaneously hypertensive rats, the C-fiber central pathway was impaired compared with normotensive rats. These observations would suggest that the C-fiber central pathways play a role in the long-term regulation of arterial pressure. However, the intraperitoneal injection of resiniferatoxin to chronically ablate C-fiber baroreceptors in normotensive rats did not lead to an elevation in arterial pressure. The electrical activation of C-fiber baroreceptors remains an important target for future application of BAT in hypertensive patients.
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