The Effect of Angiotensin II Receptor Blockade on Insulin Sensitivity and Sympathetic Nervous System Activity in Primary Hypertension

Abstract

The objective of this study was to investigate the effect of Losartan (NK-954, DuP-753), a new selective angiotensin II receptor antagonist, on insulin sensitivity and sympathetic nervous system activity in patients with severe primary hypertension. Five patients with a record of diastolic blood pressure (DBP) ± 115 mmHg, currently either untreated or with DBP > 95 mmHg on antihypertensive treatment, were examined in an open study with the euglycemic glucose clamp examination before and after being treated with Losartan for an average of 6 weeks. The glucose disposal rate increased from 6.2 ± 2.6 to 7.9 ± 2.6 mg/kg x min (27%, p < 0.05) during treatment with Losartan. The insulin sensitivity index (glucose disposal rate divided by mean insulin concentration during clamp) increased from 7.7 ± 4.5 to 10.1 ± 4.1 arbitrary units (30%, p < 0.05). Plasma noradrenaline decreased from 1.87 ± 0.53 to 1.11 ± 0.13 nmol/1 (40%, p < 0.05), while plasma adrenaline was unchanged (0.23 ± 0.10 vs. 0.22 ± 0.11 nmol/1, n.s.). Mean blood pressure decreased from 132 ± 10 to 119 ± 13 mmHg (p < 0.05) and heart rate was unchanged during treatment with Losartan. Thus, antihypertensive treatment with the new selective angiotensin II receptor antagonist Losartan seems to improve insulin sensitivity. A decrease in plasma noradrenaline on Losartan suggests a sympathicolytic effect which together with vasodilation may explain the fall in blood pressure and the improvement in insulin sensitivity.

Key Words:

• angiotensin II
• hypertension
• insulin resistance
• Losartan
• noradrenaline