Effects of dietary salt intake on endothelium-dependent and endothelium-independent relaxations in aortas of spontaneously hypertensive rats

• Published in: Japanese Journal of Pharmacology 1996, Vol.71 (suppl.1), p.131-131
• Main Authors: Kagota, Satomi, Yamaguchi, Yu, Mi, Kwon Young, Shinozuka, Kazumasa, Kunitomo, Masaru
• Format: Article
• Language: eng ; jpn
• ISSN: 0021-5198
• DOI: 10.1016/S0021-5198(19)36762-9

Male 4-week-old spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats were fed either a normal (0.3% NaCl) or a high (8% NaCl) salt diet for 5 weeks. The high salt diet significantly increased blood pressure in both SHR and WKY rats. Endothelium-dependent relaxations in response to acetylcholine (ACh) were significantly impaired in aortic rings from SHR fed the high salt diet as compared with the normal salt diet. The impaired relaxation was significantly reversed by pretreatment with either indomethacin (10^-5 M, 15 min), a cyclooxygenase inhibitor, or ONO 3708 (10^-6 M, 15 min), a TXA_2 /PGH_2 receptor antagonist. Endothelium-independent relaxations in response to sodium nitroprusside (SNP) were slightly but significantly impaired. In contrast, in aortic rings from WKY rats, the high salt diet affected neither endothelium-dependent nor endothelium-independent relaxations. These results indicate that dietary salt intake in SHR increases syntheses/release of a vasoconstrictor prostanoid(s) from the endothelium and diminishes responsiveness of smooth muscle cells for endothelium-derived relaxing factor (nitric oxide). These changes may be associated with aggravation of hypertension caused by the high salt diet.