AIM:To observe the effects of intravenous and intracerebroventricular injection of endomorphin-1(EM-1)on the left ventricular function in anesthetized rats and to assess its mechanism.METHODS:The left ventricular function was observed by inserting a catheter from right carotid artery into left ventricle after iv or civ injection of EM-1in anesthetized rats.The effects of iv or civ of various blockers,naloxone,cyprodime and atropine,on the left ventricular function caused by EM-1were observed.The level of NO...