ヒトにおけるL-arginineの体血行動態，心筋酸素消費量および心臓エネルギー効率に対する効果

Effects of L-arginine on Systemic Hemodynamics, Myocardial Oxygen Consumption and Cardiac Energy Efficiency in Humans

　L-arginine急性投与（0.5g／kg,30分間で点滴静注）前後の心血行動態を検討した．非定型的胸痛患者11名（平均年齢：60±2歳；Mean±SE）を対象とした．L-arginine投与により血中citrulline濃度は40から53nmol／mlへと増加した．肺動脈楔入圧，肺動脈圧および心拍数は不変，平均血圧は6％低下した．心係数は3.1L／min／m²から23％増加，1回拍出係数も43mlから16％増加，肺血管抵抗は不変で全末梢血管抵抗は1,577 yne-sec—cm⁻⁵から21％減少した．冠血流量は87ml／Minから12％増加，冠血管抵抗は1.42 unitから12％減少した．心筋酸素消費量，心臓エネルギー効率は不変であった．L-arginineは反射性の心拍数増加や心筋酸素消費量増大を来すことなく後負荷軽減効果により心機能を改善する．そして，心臓エネルギー効率には影響を与えない．

We examined the effects of intravenous infusion of L -arginine (0.5g/kg, 30 min) on systemic hemodynamics, myocardial oxygen consumption and cardiac energy efficiency in 11 patients with atypical chest pain. Serum citrulline concentration increased (p＜0.05) from 40±41 to 53±4 nmol/ml after L-arginine administration. L-arginine resulted in decreases (p＜0.05) in mean arterial pressure by 6% from 104 ±3 mmHg without changes in heart rate. Cardiac index and stroke index increased by 23% (p＜0.01) and by 16% (p＜0.05) respectively. Sys-temic vascular resistance decreased (p＜0.05) by 21%but pulmonary vascular resistance did not change. Great cardiac vein flow increased by 12% (p＜0.01) and coro-nary vascular resistance decreased by 12% (p＜0.05). Both myocardial oxygen consumption and cardiac energy efficiency remained unchanged before and after L-arginine administration. Thus, L-arginine results in peripheral and coronary vasodilation and increases in cardiac output without changes in heart rate, myocar-dial oxygen consumption, or cardiac energy efficiency, suggesting beneficial hemodynamic effects in humans.