Affiliations: Department of Neurosurgery, Nagoya Daini Red Cross Hospital, Nagoya 466, Japan | Department of Neurosurgery, Nagoya University, Nagoya 466, Japan
Abstract: Effect of nitric oxide (NO) on vasomotor tone of cerebral parenchymal arterioles was studied in rats. Then, the role of NO was clinically investigated in the pathogenesis of progressive cerebral vascular occlusive disease, moyamoya disease. In rat, the cerebral arterioles, about 30–60 μm in diameter, were dilated by L‐arginine, a precursor of NO, at concentrations as low as 0.1 μmol with maximal dilation of 14% at 100 μmol. The arterioles were constricted by NG‐monomethyl‐L‐arginine (L‐NMMA), a NO synthesis inhibitor. Superoxide dismutase, which seems to protect NO from inactivation, increased sensitivity of L‐arginine. Compared with control specimens of cerebral spinal fluid (CSF) obtained from 16 patients, concentrations NO metabolites in the CSF of 23 patients with moyamoya disease were significantly higher. NO metabolites concentrations obtained during initial surgery decreased during a second, contralateral procedure. NO plays an important role in the regulation of basal tone of cerebral parenchymal arterioles and contributes to the increase in collateral circulation in cerebral occlusive disease like moyamoya disease. Vascular bypass surgery can reduce NO metabolites together with abnormal collateral circulation.
