| Project/Area Number |
09670751
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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 |
Circulatory organs internal medicine
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| Research Institution | Keio University |
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Principal Investigator |
KUMAGAI Hiroo Keio University, School of Medicine, Instructor, 医学部, 助手 (50170048)
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| Co-Investigator(Kenkyū-buntansha) |
OSHIMA Naoki Keio University, School of Medicine, Assistant, 医学部, 助手 (20265789)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1998: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | hypertension / sympathetic nervous center / rostral ventrolateral medulla / whole-cell patch-clamp technique / excitatory postsynaptic potential / brainstem-spinal cord preparation / regularly firing neuron / network / 摘出脳幹脊髄標本 / パッチクランプ / 膜電位 / ペースメーカーニューロン / ルシファーイエロ-染色 |
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| Research Abstract |
Intracellular recordings were performed by the whole-cell patch-clamp technique to study the electrophysiological properties of putative presympathetic neurons in the rostral ventrolateral medulla (RVLM) and to determine whether the changes in electrophysiological characteristics of RVLM neurons contribute to genesis of hypertension. We utilized the neonatal rat brainstem-spinal cord preparation, in which the sympathetic neuronal network is thought to be preserved, unlike in slice preparation.
1. We classified and characterized RVLM presympathetic neurons into 3 types. (I) 'regularly firing neurons (n=20), which showed ramp depolarization and frequent action potentials (APs, 3.6 * 1.1 spikes/sec) with rare excitatory postsynaptic potentials (EPSPs) ; (2) 'irregularly firing neurons' (n=106), which exhibited many EPSPs and inhibitory PSPs that modulated the firing rate ; (3) 'silent-type neurons' (n=25), which discharged APs only during current-induced depolarization.
2. All of regularly
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firing neurons retained their regular discharges during low-Ca^<2+>-high-Mg^<2+> superfusion that blocks synaptic inputs, whereas the discharge in 8 of 12 irregularly firing neurons was abolished. These results suggest that the regularly firing neurons discharge independently of synaptic inputs.
3. After stimulation of intermediolateral cell column (IML) at the Th2 level, 33 of 151 RVLM neurons showed antidromic APs with a constant latency. Nineteen of 31 RVLM neurons were inhibited or potentiated by vagal afferent stimulation.
In summary, three types of RVLM presympathetic neurons were characterized by the whole-cell patch-clamp technique in the brainstem-spinal cord preparation, in which we confirmed that pathway from vagal afferents to the IML through the RVLM was preserved. Since antidromic APs and the responses to vagal afferent stimulation were demonstrated in some neurons of all 3 types, all types of RVLM neurons potentially constitute a critical part of the sympathetic neuronal network. Less
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