- 作者: Shiu-Jen Chen Chin-Chen Wu Mao-Hsiung Yen
- 作者服務機構: Department of Pharmacology, Natlonal Defense Medical Center, Taipei, Taiwn, ROC
- 中文摘要: --
- 英文摘要: Exercise training has reversible beneficial effects on car-diovascular diseases, e.g. hypertension, which may re-suit from a decrease in systemic vascular resistance. Thepurpose of this study was to investigate possible mecha-nisms associated with the changes in vascular reactivityin large and small arteries with vasoconstrictors andvasodilators in rats after exercise. Wistar-Kyoto rats weretrained for 8 weeks (Ex group) on a treadmill and com-pared with sedentary counterparts (Sed group). After themeasurement of blood pressure and heart rate at 8weeks, rat mesenteric arteries and thoracic aortas wereexcised and prepared as rings for this study. In addition,special care was taken not to damage the endothelium ofthe preparations. Our results showed that exercise train-ing for 8 weeks (1) not only prevented an increase inblood pressure but also caused a fall in heart rate, (2) at-tenuated the contractions induced by both prostaglandinF (PGF ) and high K+ in the mesenteric artery, butreduced the PGF -induced contraction in the aorta only,(3) enhanced the relaxation elicited by acetylcholine(ACh) in both mesenteric arteries and aortas, and (4) in-creased nitrate [an indicator of nitric oxide (NO) forma-tion] in plasma. The enhancement of ACh-induced relax-ation in the mesenteric arteries in the Ex group was sup-pressed by pretreatment with N -nitro-L-arginine meth-yl ester (L-NAME), tetraethylammonium (TEA; a nonse-lective inhibitor of K+ channels) or charybdotoxin [CTX; aselective inhibitor of large-conductance calcium-acti-vated K+ (BK ) channels], whereas in the aorta thatresponse was attenuated by TEA or CTX and almostcompletely abolished by L-NAME. However, with a com-bination of L-NAME plus CTX in the mesenteric artery,ACh-induced relaxation was completely abolished in theSed group, but not in the Ex group. These results suggestthat in addition to NO, activation of BK channels in thevascular beds, at least in part, also contributes to vasodi-latation in animals with exercise training.
- 中文關鍵字: --
- 英文關鍵字: Exercise. Nitric oxide. K+ channels. Vascular reactivity. Mesenteric arteries. Thoracic aortas. Rats