等尺運動負荷に対する本態性高血圧症患者の循環動態および血漿カテコールアミン濃度の反応

Changes in systemic hemodynamics and plasma catecholamine concentrations during isometric exercise in patients with essential hypertension

　等尺運動負荷は正常血圧者では，主に心拍出量を増すことにより昇圧をもたらすとされ，この心拍出量増加は主として心拍数の増加に基づくとされている^1〜4）。固定性あるいは境界域高血圧患者について等尺運動による循環動態反応をみた報告は多くはないが，現在までの報告では，これらの高血圧患者においても等尺運動による昇圧は，主として，心拍出量の増加によるとされている^{9〜13）13）}。われわれは本態性高血圧症患者と正常血圧者につき等尺運動に対する循環動態の反応を比較したところ，両者間では異なった循環動態の反応が観察された。本研究では，等尺運動負荷に対する本態性高血圧症患者の循環動態および血漿カテコールアミン濃度の反応を検討し，正常血圧者と比較したので報告する。

Mean arterial pressure (MAP), cardiac output (CO), total peripheral resistance (TPR), and plasma concentrations of norepinephrine (PNE) and epinephrine (PE) were measured in 17 patients with essential hypertension (EH) and 16 nor-motensive subjects (NT) before and 3 minutes after isometric exercise (30% of maximal handgrip). Increases in MAP and HR were both significant in the two group, and the increase in MAP was greater in the hypertensive than in the normotensive groups (p<0.02). Changes in CO were 15±2 (SE) % (p<0.001) in the normotensive group and 7±2% (p<0.01) in the hypertensive group. The difference was significant (p<0.02). Meanwhile, changes in TPR were significantry greater in the hypertensive group (19±3%, p<0.001) than in the normotensive group (3±2%, ns) with a p-value of less than 0.001. In the pooled subjects, there was a significant correlation between initial TPR and changes in TPR (r=0.51, p<0.01) or percent changes in CO (r=0.37, p<0.05). Increases in PNE (NT : 48±16 ; EH : 130±45%) and PE (NT : 45±15 ; EH : 92 33%) were not signifi-cantly different in the two groups. Moreover, changes in each hedynamic paramenters were comparable in hypertensive patients in WHO stage I and those in WHO stage II. The results suggest that hemodynamic responses to isometric exercise are different in normotensive subjects and patients with essential hypertension, and that the enhanced responses of the resistant vascular beds to sympa-thetic stimuli may be related to the inceased pressor responses in the hypertensive patients. It is also indicated that hypertensive patients in WHO stage I and those in WHO stage II may respond simi-larly to isometric exercise.