Mediative effect of ?-opioid receptor on blood pressure in the rats / 中国药理学通报

ABSTRACT

Aim To investigate the effects of U50488H,a selective ?-opioid receptor agonist,on the blood pressure in the rats and explore their mechanisms.Methods Heart rate(HR),arterial blood pressure(ABP),left ventricular pressure(LVP),contractive function(+ dp/dt_(max)) and diastolic function(-dp/dt_(max)) were examined in rats.Physiological experimental technique was used to collect urine and to determine the volume of urine output;isolated artery perfusion technique was used to investigate the direct action of U50488H on abdominal aorta of rats.Results HR,ABP,LVP and ?dp/dt_(max) in rats were decreased with the administration of U50488H;the urine volume increased significantly with the administration of U50488H.U50488H induced a dose-dependent vasodilation in the aortic artery.These effects of U50488H were totally abolished by nor-BNI,a selective ?-opioid receptor antagonist.Conclusion Stimulation of ?-opioid receptor with U50488H depresses the blood pressure mainly by reducing the strength of cardiac muscle,enhancing the urine volume and relaxing the vessel.