The Role of the Elastic and the Viscous Wall Properties in the Mechanics of Elastic and Muscular Arteries

In an endeavour to understand the mechanical properties of blood vessels, many different human and animal arteries have been studied in vitro and in vivo over the last two decades. Most investigations have been related to the elastic properties of arteries while, until recently, detailed analyses of the viscous wall properties and their dependence on circumferential wall stress, smooth muscle content and smooth muscle tone have been lacking. The aim of the present investigation was to study these interrelations, on the one hand in an elastic artery — here the abdominal aorta of the rat, which contains only small portions of smooth musculature — and on the other in a muscular artery — here the rat tail artery, the wall of which consists largely (75%) of muscle fibres. In each artery two very different degrees of smooth muscle tone were induced by the respective actions of norepinephrine and papaverine.