Endothelin-A Receptor Antagonism Promotes Decreased Vasodilation but has no Differential Effect on Coronary Artery Compliance in Hypertensive Patients

The importance of endothelin-1 in the pathophysiology of essential hypertension is unclear. We therefore examined whether there is a differential effect of endothelin-A antagonism on vasodilation and coronary artery compliance in hypertensive compared to normotensive patients. We examined atherosclerotic non-stenotic arteries from 18 non-diabetic, 10 normotensive patients and eight hypertensive patients, before and after intracoronary infusion of BQ-123 (6 μmol), an endothelin-A receptor antagonist. The systolic and diastolic artery lumen area in the proximal segment was measured using an intravascular ultrasound catheter. Systolic blood pressure decreased only in hypertensive patients (F = 5.44, P = 0.03), after BQ-123 administration. The diastolic artery lumen increased from 8.9 ± 2.9 mm at baseline to 10.8 ± 3.0 mm after BQ-123 administration (P < 0.05) in normotensive patients and from 10.6 ± 4.6 mm to 10.8 ± 4.0 mm (P = NS) in the hypertensive patients (F = 3.98, P = 0.01). The respective values for the systolic artery lumen, in the two groups, before and after BQ-123 were10.2 ± 3.4 mm and 12.7 ± 3.2 mm (P < 0.01) in the normotensive group and 12.0 ± 5.5 mm and 12.8 ± 5.0 mm (P = NS) in the hypertensive group (F = 3.37, P = 0.08). Artery compliance did not have a differential response to BQ-123. In conclusion, endothelin-A antagonism causes decreased vasodilation but does not have a differential effect on coronary artery compliance in hypertensive patients.