The association between resting heart rate, cardiovascular disease and mortality: evidence from 112,680 men and women in 12 cohorts.
BACKGROUND The aim of the study was to evaluate the impact of different plasma glucose levels on heart rate (HR) in experimental rats with acute myocardial infarction (AMI). METHODS One hundred and twenty-one male Wistar rats were randomly divided into AMI group (n = 70) and sham-operation group (n = 51). Both groups had low, normal and high glucose levels, respectively. In the former group, hypertonic glucose was injected into the rats to make their blood glucose levels above 16 mmol/L and insulin below 3.3 mmol/L; then, the left anterior descending artery was ligated. In the later group, the models of different blood glucose levels were the same as the former ones, but false operations, thread without ligating, were given to the rats. Electrocardiogram and troponin I (TnI) confirmed that the models were prepared successfully. Electrocardiogram expression of AMI was the formation of Q-wave in over three adjacent leads and abnormal elevation of TnI. RESULTS The HR of the rats in the hypoglycemic group is higher than that of the hyperglycemic group and normal blood glucose group before AMI (P < 0.05). The HR of the hyperglycemic rats is higher than that of the hypoglycemic group and normal blood glucose group after AMI (P < 0.05). In the hypoglycemic group, the HR of the rats who suffered from AMI was lower than that of the rats of the sham group (P < 0.05). CONCLUSION Hypoglycemia allows faster HR and the HR in the rats with hyperglycemia is higher than that in the rats with hypoglycemia among the AMI rats.