1995 Fiscal Year Final Research Report Summary
Role of Nitric Oxide in Regulation of Cerebral Circulation
| Project/Area Number |
06670666
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Neurology
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| Research Institution | Keio University |
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Principal Investigator |
AMANO Takahiro Keio University, Department of Neurology, Assistant Professor, 医学部, 専任講師 (90118901)
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| Co-Investigator(Kenkyū-buntansha) |
GOTOH Jun Keio University, Department of Neurology, Instructor, 医学部, 助手 (90245481)
MURAMATSU Kazuhiro Keio University, Department of Neurology, Instructor, 医学部, 助手 (20230005)
OBARA Katsuyuki Keio University, Department of Neurology, Instructor, 医学部, 助手 (40169363)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Cerebral circulation / Nitric Oxide / Neurogenic Control / Chemical Control / Nitric Oxide / L-NMMA |
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| Research Abstract |
The present study was undertaken to examine whether or not the NO system is involved in the regulation of cerebral blood flow. Mathod : Cats were anesthetized with an intraperitoneal injection of alpha-chloralose (50 mg/kg) and urethane (500mg/kg). Respiration was maintained by a Harvard respirator. The cranial window was placed in the skull on the left temporoparietal area. The window was used for monitoring pial vessels (A1 denotes the larger artery 100 mu in diameter) by a video camera system. Results : 1) The degree of arterial constriction by cervical sympathetic stimulation in the control group was not significantly different from that in the group during L-NMMA administration. The perivascular NO system does not modify the cerebral vasoconstriction elicited by cervical sympathetic nerves. 2) The pial arteries dilated by 10% CO_2 inhalation before L-NAME injection, but CO_2 reactivity indices of larger arteries significantly decreased at 60 minutes during L-NAME injection. Diated arteries only showed the suppression of CO_2 reactivity. The results indicate that diminution of CO_2 reactivity employing L-NAME is not due to NOS inhibition. 3) The autoregulatory response was evalated by the vasomotor index (VMI). VMI was calculated as the % change in diameter of pial vessels divided by the change of MABP in mmHg. The value of VMI (A1) were significantly decreased during the administration of L-NMMA.The decreased value of VMI returned to the control value after L-arginine administration. Therefore, NO in the endothelium seems to participate in autoreguratory response of cerebral vessels. Comments : The present investigations showed that the NO system has an important role in the regulation of autoregultoary response, but not in the chemical control by CO_2 inhalation.
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