What is the main effect of ACE inhibitors on blood vessels?

ACE inhibitors primarily function by inhibiting the angiotensin-converting enzyme, which plays a critical role in the renin-angiotensin-aldosterone system responsible for regulating blood pressure. By blocking this enzyme, ACE inhibitors reduce the production of angiotensin II, a potent vasoconstrictor. The decrease in angiotensin II levels leads to the relaxation of blood vessels, which contributes to lower blood pressure by widening (dilating) the blood vessels. This dilation decreases vascular resistance, making it easier for blood to flow through the vessels, thus ultimately reducing the workload on the heart. The relaxation effect on blood vessels is essential in the management of hypertension and heart failure.