ABSTRACT
OBJECTIVE:To study the effects of Betoloc(metoprolol)on autonomic nervous system in the heart METHODS:Using the computerized analysis system developed by our laboratory,the characteristic parameters of heart period signal(HPS)from volunteers were examined before and 3 hours after administrating Betoloc(50mg,po ) RESULTS:Betoloc could increase the mean heart period,standard deviation of heart period,high frequency components and total power of HPS'spectra,and decrease heart rate,low frequency components significantly CONCLUSION:(1)Betoloc can increase standard deviation of heart period or heart rate,which means increasing irregularity of heart rate It is the basic reason of increasing high frequency components of HPS'spectra and is also the basic reason of increasing cholinergic nervous activity;(2)Betoloc can decrease tension of sympathetic nerves,increase tension of parasympathetic nerves,and increase tension of autonomic nervous system in the heart