1996 Fiscal Year Final Research Report Summary
Mechanisms of long-term regulation of blood pressure by the central nervous system
| Project/Area Number |
06670057
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
General physiology
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| Research Institution | Kagawa Medical University |
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Principal Investigator |
NISHIDA Yasuhiro Kagawa Medical University, Department of Physiology, Associate Professor, 医学部, 助教授 (90172668)
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| Project Period (FY) |
1994 – 1996
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| Keywords | 24-hr-blood pressure / long-term control / Central Nervous System / Area Postrema / Neurohumoral Interaction / Body Fluid Balance / Vasopressin / Arterial Baroreflex |
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| Research Abstract |
Project 1. The purpose of this study is to examine whether the neurohumoral interaction at the area postrema (AP) could function to regulate arterial pressure in a long-term fashion. Vasopressin (0.25 ng/kg/min) was infused for 5 days to the AP-lesioned rabbits (APX) and the intact rabbits (INT), and then compared its effects on sodium and water balances, plasma Na concentration (PNa), plasma osmolality (Posm), mean arterial pressure (MAP), and heart rate (HR) using a metabolic cage. The balance study showed that sodium (Na) and water were hypotonically retained in INT,while not in APX.The data of PNa and Posm supported this result. No significant difference was observed in MAP between the two groups. Bradycardia was observed in INT but not in APX.No significant difference was observed in plasma vasopressin concentration between the two groups. Histological examinations using a Nissl staining method showed that the AP was completely destroyed but the major portions of the nucleus tract
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us solitarius and the dorsal motor nucleus of the vagus and the entire hypoglossal nucleus were intact. These results indicate that the neurohumoral interaction at the AP functions to enhance the water retention action of vasopressin and suppress HR in a long-term fashion, but is not strong enough to overcome other compensatory systems regulating MAP.
Project 2. Next, we examined whether the arterial baroreflex system can control MAP in a long-term fashion during physical movements. We established the measuring and analyzing system for 24-hr MAP and compared the histograms of 24-hr MAP between intact and sinoaortic denervated (SAD) rabbits. No significant difference was observed in a mode of MAP during a resting phase between the two groups. However, during a moving phase, SAD abolished an increase in a mode of 24-hr MAP which was observed in intact rabbits. This result leads to the possibility that the central nervous system may contribute to a long-term regulation of MAP during physical movements via the baroreflex system. Less
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