Peripheral action of spironolactone: plethysmographic studies

The relation between vasodilation and the blood pressure-reducing action of spironolactone was studied in a randomized, placebo-controlled, double-blind, crossover study using 9 patients with essential hypertension. Vasodilation was studied by measuring blood flow in finger and calf (representative of skin and muscle circulation) by an electrocardiographic-triggered venous-occlusion plethysmograph. Treatment with spironolactone (100 mg twice daily for 4 weeks) produced significant decreases in systolic and diastolic blood pressure without significantly affecting heart rate. Blood flow through finger and calf increased, sometimes markedly, in 6 of the 9 patients, while vascular resistance decreased. This study confirms that the antihypertensive action of spironolactone is associated with vasodilation in many patients.