健康成年，高齢者および虚血性心疾患における運動負荷時血漿NEと心血管反応の関係

Interrelation between plasma norepinephrine and cardiovascular response to exercise in healthy young adults, aged and patients with ischemic heart disease

　運動負荷試験は，古くからスポーツ医学の分野で体力テストの手段として用いられてきたが，最近では心疾患の診断やリハビリテーションの面で普及している。運動時交感神経が緊張することは従来より知られてきたが，その刺激伝達を担うノルエピネフリン（NE）の正確な測定が困難であったため，運動中の心血管反応との直接的関係は明らかではなかった。近年，高感度のNE分析法が開発され，これに伴い生体内交感神経系のベールも次第に取除かれ，その機能がより的確に理解されつつある^1,2,3）。今回，筆者らは健康成年，高齢者および虚血性心疾患（IHD）患者を対象として，安静時ならびに運動負荷時の血漿NE濃度，循環諸量を測定し，運動時NE変化と心血管反応とを対比して二，三の知見を得たので報告する。

The relationship between plasma norepinephrine concentration (NE) and cardiovascular response to supine exercise was studied in 20 healthy young adults, 13 aged and 21 patients with ischemic heart disease (IHD).

NE concentration at rest was significantly higher in the aged and IHD (p<0.005) than in the young adults (259±27, 431±60 and 159±21 pg/ml, respectively). In the young, NE exhibited exponen-tial increase and decrease associated with the chan-ges in heart rate (HR) during exercise and recov-ery, respectively. At the level of maximum exercise, NE in IHD (1347±249 pg/ml) was significantly high (p<0.005) as compared with those in the young and the aged (650±58 and 782±166 pg/ml). Thus, the degree of the increment in NE during maximum exercise was larger in IHD than in the young and the aged, while the increases in HR and systolic blood pressure (BPs) were lower in the aged and IHD (p<0.005) than in the young (changes in HR ; 48±5, 46±6 and 105±3 beats/min ; changes in BPs ; 41±7, 38±7 and 83±3 mmHg). These demonstrated that cardiac response to sympa-thetic nervous activity during exercise diminished in the aged and IHD. Beta blockade treatment in IHD has no influence on the changes in NE during exercise, but inhibited the increases in HR and BPs.