Effects Of Naloxone Of Different Dosages On The Resuscitation Of Asphyxial Cardiac Arrest In Rats

Along with the development of the theories and the methods of cardio-pulmonary cerebral resuscitation(CPCR), the level of CPCR have being elevated obviously, but some estimates indicate that the survival rate after cardiac arrest is still lower than 10% in the world. Epinephine has been administed as a drug essatial for CPCR. Especially, high dose epinephine is more benefit for recovery of spontaneous circulation, and may enhance the success rate of resuscitation of sudden cardiac arrest. However, recently more and more investigations were demonstrated that epinephrine may cause myocardial dysfunction, increase myocardial oxygen consumption and tachyarrhythmias. further more, epinephrine may result in more serious sequela and reduce the survival rate after cardiac arrest. Therefore, it is essential to look for a kind of effective drug for resuscitation. Release of endogenous opioids is part of the neuroendocrine response to stress and shock. Endogenous opioids and specifically the opioid/anti-opioid balance have been identified as major factors contributing to the course of various shock states. The concentration of serous endogenous opioids in patients with cardiac arrest may significantly increase. Naloxone is a specific opiate receptor antagonist, It can definitely block endogenous opioids, and cause extensive pharmacological effect. But in finite reports about naloxone in CPCR , most of them are about cerebral resuscitation ,less of them are about the influence of naloxone on the heart and circulation, and the effects of naloxone of different dosages on CPCR is still not clear,this study is to reseach the effects of naloxone of different dosages on the CPCR of asphyxial cardiac arrest in rats. Methods Forty Wistar rats(body weight 300+20g) were divided into four groups at random: Epinephrine group(NE,n=10),treated with epinephrine (0.2mg/kg) i.v., Small amount of Naloxone group(SN,n = 10) , treated with epinephrine (0.2mg/kg) i.v.+ Naloxone(1mg/kg) i.v.,Medium amount of Naloxone group (MN,n=10),treated with epinephrine (0.2mg/kg) i.v.+ Naloxone (3mg/kg) i.v. and Large amount of Naloxone(LN, n=10),treated with epinephrine (0.2mg/kg) i.v.+ Naloxone(5mg/kg)i.v.. endotracheal tubes were clamps to cause asphyxial cardiac arrest. NE group were given epinephrine 0.2mg/kg, Epinephrine were given again after an interval of 5 min if necessary. The others were not only given epinephrine (0.2mg/kg) , also given different dosages of Naloxone ,and were repeated many times after an interval of 30 min. Successfully resuscitated rats accepted 2-hour-period of intersive care. Blood pressure and heart rate were observed. Histological feature of myocardium were examined under light microscope and electron microscope. Results 1. In this experiment,The durations from endotracheal...