Abstract

Essential hypertension is associated with abnormal endothelial function, characterized by an imbalance between vasodilators and vasoconstrictors. The effect of antihypertensive treatment on this endothelial function is poorly known. The aim of the study was to evaluate the effect of antihypertensive treatment with the angiotensin receptor blocker irbesartan on endothelial function, assessed by strain-gauge plethysmography, in a group of essential hypertensive patients.

Fourteen essential hypertensive patients, without evidence of target organ damage were studied. Endothelial function was evaluated by strain-gauge plethysmography. Measurements of baseline forearm blood flow (FBF), the effect of increasing doses of acethylcholine (endothelium dependent vasodilation: EDV) and sodium nitroprusside (endothelium independent vasodilation: EIV) on FBF, as well as the effect of L-NMMA, a NO synthase inhibitor, on this FBF were performed at baseline and at the end of a 6 month treatment period with irbesartan (150-300 mg/day).

Irbesartan significantly decreased BP, both systolic and diastolic. Baseline forearm blood flow did not significantly change at the end of treatment. On the contrary, irbesartan promoted an increased (p=0.055) vasodilating response to acetylcholine and a non-significant increase in sodium nitroprusside-induced vasodilation. According to this enhancement in endothelium-dependent vasodilation, the effect of L-NMMA on baseline forearm blood flow was more intense (p=0.089) after irbesartan treatment. In conclusion, chronic treatment with irbesartan tend to increase both endothelium-dependent and independent responses. The effect of L-NMMA on baseline FBF suggests an amelioration of NO bioavailability. (See Table)

ParameterBaselineIrbesartanP
Systolic BP (mmHg)170±13146±14<0.001
Diastolic BP (mmHg)97±688±60.002
Baseline FBF (ml/100ml tissue/min)4.3±0.84.0±0.50.136
EDV (%)417±130470±1310.055
EIV (%)395±92436±880.328
L-NMMA decrease in FBF (%)35±1041±40.089
ParameterBaselineIrbesartanP
Systolic BP (mmHg)170±13146±14<0.001
Diastolic BP (mmHg)97±688±60.002
Baseline FBF (ml/100ml tissue/min)4.3±0.84.0±0.50.136
EDV (%)417±130470±1310.055
EIV (%)395±92436±880.328
L-NMMA decrease in FBF (%)35±1041±40.089

Sonoji-symthelobo

ParameterBaselineIrbesartanP
Systolic BP (mmHg)170±13146±14<0.001
Diastolic BP (mmHg)97±688±60.002
Baseline FBF (ml/100ml tissue/min)4.3±0.84.0±0.50.136
EDV (%)417±130470±1310.055
EIV (%)395±92436±880.328
L-NMMA decrease in FBF (%)35±1041±40.089
ParameterBaselineIrbesartanP
Systolic BP (mmHg)170±13146±14<0.001
Diastolic BP (mmHg)97±688±60.002
Baseline FBF (ml/100ml tissue/min)4.3±0.84.0±0.50.136
EDV (%)417±130470±1310.055
EIV (%)395±92436±880.328
L-NMMA decrease in FBF (%)35±1041±40.089

Sonoji-symthelobo

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