Objective: To observe the plasticity of pain threshold in rats with myocardial infarction, to explore the effect of nicotine on visceral pain and whether it has a protective effect on ischemic myocardium.
Method: 30 SPF-grade Sprague-Dawlay healthy male rats, weighing 180~200g, were divided into sham operation group, model group and nicotine treatment group based on the principle of random numbers. The rats in each group were observed electrocardiogram (ECG), pain threshold (thermal pain threshold PWL, mechanical pain threshold PWT), changes in left ventricular pressure amplitude, heart body mass index, and changes in creatine kinase isoenzyme (CK-MB).
Results: Compared with the sham operation group, the mechanical pain threshold of the model group became smaller and the thermal pain threshold became larger (P<0.05); while plasma CK-MB activity, heart body mass index, and left ventricular pressure were significantly increased (P<0.05) . Compared with the model group, the nicotine treatment group had higher mechanical pain threshold and lower thermal pain threshold; plasma CK-MB activity, heart body mass index, and left ventricular pressure were significantly reduced (P<0.05), and the difference was statistically significant.
Conclusion: Nicotine can relieve the symptoms of myocardial ischemia and visceral pain caused by ischemia in rats with myocardial infarction. Its mechanism may be related to the activation of cholinergic anti-inflammatory pathways, thereby improving the pain in rats. And protect the rat heart.