抄録
Background: Hypertension impairs endothelium-dependent vasodilation with aging. Aim: To examine age-related participation of nitric oxide (NO) and endothelium-derived hyperpolarizing factor (EDHF) in spontaneously hypertensive rats (SHRs). Methods: Coronary small arteries (100μm<) and arterioles (<100μm) in in vivo beating hearts of 6-, 12- and 28-week-old SHRs (n=41) and age-matched Wistar-Kyoto rats (WKYs) (n=38) were observed by our intravital microscope with CCD camera under cyclooxygenase blockade. Coronary vascular responses to acetylcholine (ACh) were examined under two conditions; ACh and ACh plus L-NAME. Results: Vasodilation of both arterioles and small arteries was maintained by 12 weeks in SHRs, but NO-mediated dilation decreased by 26% in arterioles and 34% in small arteries at 28 weeks compared to control. In 28 week-old-SHRs, contribution of NO-mediated vasodilation decreased by 24% in arterioles and 45% in small arteries, while contribution of EDHF-mediated dilation decreased by 27% in arterioles and 56% in small arteries. In WKYs, EDHF-mediated dilation decreased in small arteries by 31% of control, although ACh-dependent dilation was maintained by 28 weeks. Conclusion: Hypertension with aging at 28 weeks induces endothelial impairment of both NO and EDHF in small arteries as well as arterioles, while in normal rats, aging at 28 weeks attenuates EDHF-mediated dilation only in small arteries. [Jpn J Physiol 54 Suppl:S90 (2004)]
