| Co-Investigator(Kenkyū-buntansha) |
YURA Takafumi Kagawa Medical School, Second Department of Internal Medicine, Research Associat, 医学部付属病院, 助手 (40200878)
BANDAI Hisashi Kagawa Medical School, Second Department of Internal Medicine, Research Associat, 医学部, 助手 (60208725)
NAGATSUKA Kazuyuki Kagawa Medical School, Clinical Laboratory, Research Associate, 医学部付属病院, 助手 (70189140)
MATSUO Hirohide Kagawa Medical School, Second Department of Internal Medicine, Professor, 医学部, 教授 (90028514)
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| Research Abstract |
The cerebral circulatory reserve capacity is important to prevent cerebral ischemia. A reduction of the reserve capacity of cerebral circulation with ageing might be an important risk factor for the occurrence of ischemic cerebrovascular diseases in the elderly. We have been studied the hyperfrontality of the regional cerebral blood flow (rCBF) and vascular carbon dioxide reactivity and its disturbances with ageing up to the present time (14th International Salzburg Conference on Cerebrovascular Diseases, 1988, Second Annual Meeting of Japanese Society of Cerebral Circulation and Metabolism, 1990).
The aim of this study is to investigate the mechanism of the occurrence of cerebral infarctions in deep perforating cerebral arteries. We evaluated quantitatively of 1) carbon dioxide reactivity of tomographic regional cerebral blood volume (rCBV) by use of Tc-99m labeled red blood cell (RBC) Single-photon Emission CT (SPECT), and of 2) tomographic rCBF/CBV ratios by the evaluations of tomogr
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aphic rCBF with I-123 IMP SPECT, for the evaluations of changes of these parameters with ageing and selective vulnerability by the differences of regions.
As the result, 1) with respect to the rate of in vivo RBC labeling, we got 60-70 % labeling rate which was insufficient for the quantitative evaluations of rCBV, for which at least 90 % of labeling rate were necessary. 2) With respect to the measurements of tomographic rCBF, we evaluated semiquantitative rCBF indices of redistribution, asymmetry, and filling-in, in each region of interest of 2 x 2 cm. 3) The increase of arterial carbon dioxide tension by inhalation of 5 % carbon dioxide was insufficient for the constant evaluation of cerebrovascular carbon dioxide reactivity. It was difficult to maintain the arterial concentration to be constant for 30 minutes during the rCBF measurements. We observed an elevation of blood pressure, which was the unfavourable systemic effect by the carbon dioxide inhalation. The intravenous infusion of NaHCO_3 solution, instead of carbon dioxide inhalation, may cause metabolic alkalosis, which may be different from the true cerebrovascular carbon dioxide reactivity induced by carbon dioxide inhalation. The evaluations of tomographic cerebrovascular carbon dioxide reactivity were therefore unsuccessful. Less
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