Effects of rat urotensin Ⅱ on coronary flow and myocardial eNOS protein expression in isolated rat heart

• 来源期刊: 中国药理学报（英文版）
• 关键词: urotensin Ⅱ nitric oxide synthase nitric oxide heart function tests coronary circulation rats
• 年，卷（期）: 2004,（11）
• 页码范围: 1444-1449
• 页数: 6页
• 语种: 英文

摘要

AIM: To examine the effects of urotensin Ⅱ, a recently discovered endogenous peptide, on coronary flow (CF),cardiac function, and endothelial nitric oxide synthase (eNOS) expression in isolated rat hearts. METHODS: Heart was isolated and perfused retrogradely via the aorta in Langendorff mode. Rat urotensin Ⅱ was administered in the perfusion solution. The eNOS content in myocardium was determined by Western blot. RESULTS: Rat urotensinⅡ had no effect on the heart rate, left ventricular systolic pressure, left ventricular end-diastolic pressure, or±dp/dtmax. While rat urotensin Ⅱ dose-dependently increased CF. CF was increased by 11.43 %, 6.67 %, 6.62 %,6.56 %, 6.36 %, and 5,86 % respectively in a time-dependent manner at 5, 10, 15, 20, 25, and 30 min after injection of rat urotensin Ⅱ 6.66× 10-2 μg. The maximal effect on CF was found at 5 min following urotensin Ⅱ administration.NG-nitro-L-arginine methyl ester (L-NAME) did not prevent the increased CF in response to urotensin Ⅱ. Rat urotensin Ⅱ dose-dependently increased the cardiac eNOS protein expression and this effect was not inhibited by L-NAME. CONCLUSION: Rat urotensin Ⅱ did not alter cardiac function but increased CF and the amount of myocardial eNOS protein in the isolated rat heart. The increased CF was independent of the involvement of eNOS.