Abstract
Background: Hypertension is associated with remodeling and mechanical alterations of resistance arteries. 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 objective of the present study was to evaluate the dilation responses of small mesenteric arteries (SMA) from spontaneously hypertensive rats (SHR) at various levels of intraluminal pressure. Methods and Results: SMA segments from Wistar Kyoto (WKY) rats and SHR were pressurized using pressure myography. Endothelium-dependent and -independent dilation responses of the SMA were examined under 3 different intravascular pressures (50, 80 and 120 mmHg). Endothelium-dependent dilation was evaluated by measuring vasodilator responses to increasing doses of acetylcholine or increases in intraluminal flow rate. Endothelium-independent vasodilator function was examined by using sodium nitroprusside. The results indicate that both endothelium-dependent and -independent dilation responses of SMA from WKY progressively decrease with increased intravascular pressure. In contrast, all dilatation responses of the SMA from SHR were enhanced at higher intraluminal pressures. Conclusions: These findings of differential sensitivity to luminal pressure should be considered during in vitro examination of vessels from normotensive and hypertensive subjects. (Circ J 2009; 73: 2091-2097)
