Collagen I and III and mechanical properties of conduit arteries in rats with genetic hypertension

Conduit arteries of hypertensive rats are thicker and stiffer than those of normotensive controls. The possible role played by collagen type I and II subtypes in the mechanism of arterial stiffness remains unknown. The caroti d and aortic arterial wall of rats of Japanese (Wistar-Kyoto and spontaneou sly hypertensive rats) and Lyon (normotensive and hypertensive rats) origin were studied. The stiffness of the carotid wall material (ultrasound), the histomorphometry of the aortic wall with the content in collagen I and III subtypes and their corresponding mRNA were analyzed. Independently of hype rtension, the Japanese group differed from the Lyon group by a stiffer caro tid wall material at any given value of wall stress; a lesser degree of aor tic hypertrophy with a higher percentage of elastin, and a higher density o f collagen III but not of collagen I. All other hemodynamic and histomorpho metric parameters were affected by both the origin of the rats (Japanese vs . Lyon) and the presence of hypertension. Large artery stiffness in genetic ally hypertensive rats was not only influenced by hypertension itself, but also by differences in the contents of collagen subtypes which are also fou nd in their corresponding normotensive controls.