Aortic collagen, aortic stiffness, and AT1 receptors in experimental and human hypertension

Converting-enzyme inhibitors decrease the collagen content of the arterial wall in various models of hypertension in rats. Angiotensin II induces collagen production in culture cells. Whether the decrease in collagen induced by converting-enzyme inhibition is due in vivo to pressure mechanisms or to nonhemodynamic factors or a combination of both remains the subject of discussion. In this review, it will be shown that (i) converting-enzyme inhibition prevents the accumulation of aortic collagen in hypertensive rats independently of blood pressure changes, (ii) prevention of aortic collagen accumulation in hypertensive rats is obtained through blockade of angiotensin II formation involving AT1 receptors, and (iii) in hypertensive humans, increased aortic stiffness is associated with AGTR1 receptor polymorphism independently of age and blood pressure.