Study on the Regulatory Mechanism of Automatic Nerve on the Rest Heart Rate in Treadmill Exercise and Obese Rats

Objective:This study seted up a treadmill exercise obese rats modal by being fed with high fat and sugar food and following the fitness test.The aim was going to find the effects of exercise and obesity on the rest heart rate(HR)regulation of the automatic nerve in rats.It is going to find a sensitive index for evaluating the risk of cardiovascular disease.Methods:Four weeks old male rats were divided into two groups randomly:Control group(C Group)was fed with control food;the left rats were fed with high fat and sugar food.After 8 weeks,the obese rats were separated from the rats with high fat and sugar food as F Group and subdivided into three groups:FC Group rats did no exercise;FM Group rats did Mid-intensity exercise;and FH Groups did High-intensity exercise.The obese rats did 2 weeks adaptive running and then were trained for other 8 weeks.HR and the change of HR after blocking the automatic nerve were tested respectively.Elisa and RT-PCR were used to test the concentration of M2 receptor,RGS6 and Kir3.4.Results:1)After 8 weeks,HR of F group was significantly lower than the rats in C Group(P<0.05).2)HR of C Group at 18 weeks was significantly lower than at 8 weeks(P<0.05),but it did not happen in FC Group.And there was no significant difference in HR at 18 weeks between C Group and FC Group.3)The change of HR was not significant different between C group and FC Group and among the obese groups.4)Kir3.4in FC Group was significant more than in C Group(P<0.05).5)M2 receptor mRNA in FC Group was less than in C Group,but RGS6 mRNA in FC Group was more than in C Group.6)M2 receptor mRNA in both FM Group and FH Group was less than in FC Group.Conclusion:During the development of the obese,the main effect of automatic nerve on the rest heart rate regulation changed from vagal nerve to sympathetic nerve.8 weeks exercise had no effect on the rest heart rate regulation of automatic nerve.