本態生高血圧におけるＡＣＥ阻害薬ｌｉｓｉｎｏｐｒｉｌおよびβ１選択性β遮断薬ｂｅｔａｘｏｌｏｌの循環動態上の効果

Abstract

Hemodynamic effects of lisinopril, a new angiotensin converting enzyme inhibitor, and betaxolol, a new β1-selective β-blocking agent, were evaluated in 21 outpatients with essential hypertension (WHO I / II stage) introducing them orally for six wks. Lisinopril (mean dose, 13.5 ±2.2 (SEM) mg/day) and betaxolol (8.4 ± 1.9 mg/day) reduced blood pressure (lisinopril, 176/103 ± 7/2 to 154/88±6/3 mmHg, P<0. 01; betaxolol, 171/107 ± 5/2 to 152/92±5/2 5/2 mmHg, P< 0.005) with different effects on heart rate ; betaxolol reduced heart rate significantly (66 ± 2 to 61 ± 3 bpm, P< 0.01) but lisinopril did not (71 ± 3 to 71 ± 3 bpm). These two drugs did not induce any significant change in circulating blood volume (measured using 131I-labeled human serum albumin) (lisinopril, 2. 95 ± 0. 17 to 2. 93 ± 0.15 l/m2 ; betaxolol, 2.80± 0.08 to 2.77± 0.09 l/m2) and cardiac output (measured using 99mTc in vivo labeled red cells) (lisinopril, 3.19 ± 0.20 to 3. 19 ±0.19 l/min/m2 ; betaxolol, 3.23 ± 0.09 to 3.19 ±0.16 l/min/m2). Both of them induced a slight and insignificant increase in left ventricular ejection fraction (LVEF) and reduced total peripheral resistance index (lisinopril, 3, 302 ± 196 to 2, 828 ± 150 dyn·sec·cm-5·m2, P<0.01; betaxolol, 3, 179 ± 75 to 2, 856 ± 167 dyn·sec·cm-5·m2), though the decrease in the betaxolol group was not significant.These effects in the lisinopril-treated group may be attributable to angiotensin converting enzyme inhibiting activity mainly in vascular beds. As β1-selective β-blocking agents without vasodilating properties, such as atenolol and metoprolol, were reported to reduce cardiac pump function without decrease in peripheral resistance, and celiprolol, one with vasodilating properties, was reported to reduce peripheral resistance in essential hypertension, these results obtained in the betaxolol-treated group warrant a further investigation on its vasodilating properties.