The Effects of Nitric Oxide on the Intrinsic Heart Rate in Conscious Rats

• Main Authors: Yih-Yin Farng, 房逸雲
• Other Authors: 楊戍聰
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/35282599478926213552

碩士 === 國防醫學院 === 生理學研究所 === 88 === Recent evidence has demonstrated that nitric oxide is an important second messenger in the cardiovascular and central nervous systems. Although the role of NO in modulating myocardial contractility has been extensively investigated, the effects of NO on the intrinsic heart rate（IHR） have received comparatively little attention. Whether nitric oxide is essential for the physiological control of intrinsic heart rate remains to be investigated. Therefore, the aim of this study was to examine the relationship between the intrinsic heart rate and NO in conscious rats. The intrinsic heart rate was measured during inhibition of autonomic influence on the heart by an intravenous injection of propranolol（10 mg/kg）and atropine（10 mg/kg）. After autonomic blockade NG-nitro-L-arginine-methyl ester （21 mg/kg）increased mean blood pressure by 29.9 % but decreased intrinsic heart rate by 4.7 % . Autonomic blockade did not influence the decreased mean blood pressure（37.7 %）and increased intrinsic heart rate（11.6 %）to nitroglycerin（300 μg/kg）. Our results suggest that nitric oxide can affect intrinsic heart rate.