頁籤選單縮合
題 名 | Chronic Exercise Enhances Vascular Responses to Clonidine in Rats by Increasing Endothelial α[feaf]-Adrenergic Receptor Affinity |
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作 者 | Chen,Hsiun-ing; Cheng,Shu-yuan; Jen,Chauying J.; | 書刊名 | 中國生理學雜誌 |
卷 期 | 42:2 1999.06[民88.06] |
頁 次 | 頁61-66 |
分類號 | 361.18 |
關鍵詞 | Adrenergic agonist; Arteries; Endothelial receptors; Nitric oxide; Wistar rats; |
語 文 | 英文(English) |
英文摘要 | Chronic exercise increases endothelium-dependent vasodilating responses. To investigate whether endothelial α□-adrenergic receptor upregulation is involved in the enhancement of clonidineinduced vasorelaxation by chronic exercise, 4-week-old male Wistar rats were used. They were divided into control and exercise groups. The trained animals ran on a treadmill at a moderate intensity for 60 min per day, 5 days per week for 10 weeks in total. Resting heart rates were measured by a tail-cuff method to confirm training effects. After training, rings of the thoracic aorta were prepared to evaluate vasodilating responses to clonidine, an α□ agonist. Released endothelium-derived relaxing factors were pharmacologically identified by treatment of N□-nitro-L-arginine, a nitric oxide (NO) synthase inhibitor, or tetraethylammonium chloride, an endothelium-derived hyperpolarization factor (EDHF) inhibitor. Receptor binding assays were performed by using □H-labeled clonidine as a tracer. We found that chronic exercise enhanced vascular responses to clonidine by stimulating the release of both NO and EDHF. It also increased the binding affinity of endothelial cell α□ receptor without changing the number of binding sites. Therefore, the elevated vasorelaxing responses to clonidine after chronic exercise may be partially resulted from an increase in endothelial α□ receptor binding affinity. |
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