Isao Nara

Effect of Different Intensities of Exercise on Endothelium-Dependent Vasodilation in Humans Role of Endothelium-Dependent Nitric Oxide and Oxidative Stress

Background—Aerobic exercise enhances endothelium-dependent vasodilation in hypertensive patients, patients with chronic heart failure, and healthy individuals. However, it is unclear how the intensity of exercise affects endothelial function in humans. The purpose of the present study was to determine the effects of different intensities of exercise on endothelium-dependent vasodilation in humans. Methods and Results—We evaluated the forearm blood flow responses to acetylcholine, an endothelium-dependent vasodilator, and isosorbide dinitrate, an endothelium-independent vasodilator, before and after different intensities of exercise (mild, 25% &OV0312;o2max; moderate, 50% &OV0312;o2max; and high, 75% &OV0312;o2max; bicycle ergometers, 30 minutes, 5 to 7 times per week for 12 weeks) in 26 healthy young men. Forearm blood flow was measured using a mercury-filled Silastic strain-gauge plethysmograph. Twelve weeks of moderate-intensity exercise, but not mild- or high-intensity exercise, significantly augmented acetylcholine-induced vasodilation (7.5±2.4 to 11.4±5.8 mL/min per 100 mL tissue; P <0.05). No intensity of aerobic exercise altered isosorbide dinitrate–induced vasodilation. The administration of NG-monomethyl-l-arginine, a nitric oxide synthase inhibitor, abolished the moderate-intensity exercise-induced augmentation of the forearm blood flow response to acetylcholine. High-intensity exercise increases plasma concentrations of 8-hydroxy-2′-deoxyguanosine (from 6.7±1.1 to 9.2±2.3 ng/mL; P <0.05) and serum concentrations of malondialdehyde-modified low-density lipoprotein (from 69.0±19.5 to 82.4±21.5 U/L; P <0.05), whereas moderate exercise tended to decrease both indices of oxidative stress. Conclusions—These findings suggest that moderate-intensity aerobic exercise augments endothelium-dependent vasodilation in humans through the increased production of nitric oxide and that high-intensity exercise possibly increases oxidative stress.

早産児における Dubowitz 神経学的評価の特徴 : 脳障害児との比較

低出生体重児57名と,新生児期に明らかな脳障害が確認された11名を対象に,出産予定日頃にDubowitz の神経学的評価を行った.発達に影響を及ぼす因子として報告されている,在胎週数,出生体重を考慮し,評価結果の比較検討を行った.評価したすべてのカテゴリーとtotal score において低出生体重児では早産・低体重の程度による影響を受けず,出産予定日での発達に差はなかった.tone,reflexes,behavior のカテゴリーでは早産児は脳障害児のスコアと比べて有意に高かった.また,tone patterns,abnormal signs では早産児と脳障害児でスコアに違いはみられず,このカテゴリーにおいて異常性との判別は難しいと考えられる.total score でみると早産児のスコアはDubowitz により報告されたカットオフ値の30 より低いスコアであり,低出生体重児での新たな基準を設定する必要が示唆された.