ACE and Hypertension: And, although a number of the classes of antihypertensive agents target the vascular smooth muscle [α-blockers, angiotensin converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), calcium channel blockers (CCBs)], until recently, there was little experimental evidence consistent with the regulation of vascular tone being an important factor for the molecular mechanism that produces hypertension (Fig. 1).