ypertension is a multifactorial, polygenic disease and is an important risk factor for the development of atherosclerosis and cardiovascular diseases. [1][2][3][4] It is well established that chronic hypertension is associated with the structural and functional changes in the resistance vasculature that are responsible for the elevated peripheral resistance in hypertension; 1,5,6 such structural alterations are termed "vascular remodeling". In the majority of hypertension models studied, the internal diameter is reduced and the wall/lumen ratio is increased in small arteries as a consequence of increased wall thickness. Vascular remodeling is also associated with altered mechanical properties such as reduced distensibility. [5][6][7] In addition, the altered balance of vasoconstrictor and vasodilator systems has an important role in augmenting systemic resistance in hypertension. 8,9 In vitro studies of small arteries from hypertensive animals and humans are widely used in the investigation of hypertension and its complications. Two experimental techniques are commonly used: (1) wire myography and (2) pressurized myography systems. 10,11 The pressurized method has several advantages, including maintenance of the vessel's cylindrical shape and better preservation of the endothelium. The structural and mechanical characteristics of the small arteries of both normotensive and hypertensive rats and humans have been evaluated at different levels of intravascular pressure by the pressurized myography technique. [11][12][13][14][15] In those studies, the small arteries obtained from hypertensive subjects were exposed to intraluminal pressures within a wide range (ie, 3-140 mmHg), and structural and mechanical properties, such as internal and external diameters, cross-sectional area, wall/lumen ratio, distensibility, circumferential wall strain or stress, were evaluated. The results have indicated that small arteries from hypertensive subjects have altered structural and mechanical properties compared with normotensives.Pressurized small artery preparations also have been used to examine the functional properties of vessels from normotensive and hypertensive rats or humans. [16][17][18][19][20][21] However, those studies, which investigated the dilatation responses of small arteries to several agonists or flow by pressurized myography, were only performed under normotensive conditions, and the "normotensive" intraluminal pressures differed among them. Small mesenteric arteries (SMA) are usually exposed to pressures of 30 or 45 mmHg, [16][17][18] whereas small arteries obtained from skeletal muscle are exposed to greater pressures. 19 Pressurized small artery preparations also have been used in several human studies: Numerous studies have investigated the mechanical and morphometric properties of small arteries obtained from hypertensive animals and humans. However, the functional properties of resistance arteries from normotensive and hypertensive subjects have only been examined under normotensive conditions. The objec...