"G um exp." in the table means before the gum chewing experiment, and "Cont exp." in the table means Table 1. Rest values of heart rate (HR), coefficient of variation in RR (CVRR), wave height of plethysmogram (WH) and coefficient of variation in WH (CVWH), and plasma adrenalinne (pad), noradrenaline (pnorad), blood sugar (BS), serum insulin (IRI) and blood lactate (LA) concentrations before the experiment. before the control experiment by mastication movement with nothing in a mouth. Values in the table are means } SD. Statistical significance of 5% level was not recognized by Student's unpaired t -test between the gum chewing and control experiments.

Fig. 1 Responses of heart rate ( HR), plethysmogram wave height ( WH), and coefficients of variations in RR intervals of ECG and wave height ( CVRR, CVWH)during chewing of gum with three different levels of hardness from the resting values in the pre-experiment ( ). Asterisks indicate significance of differences from resting values, and between the gum chewing and control experiments. Dots and bars in the figure indicate means (dot) } SE(bar).* p<0.05,** p<0.01

Fig. 2 Responses of plasma adrenaline ( pad), nor-adrenaline ( pnorad), blood sugar ( BS), serum immunoreactive insulin ( IRI), and blood lactate ( LA) concentration during chewing of gum with three different levels of hardness from resting values of the pre-experiment (A). Asterisks indicate significance of differences from resting values, and between the gum chewing and control experiments. Dots and bars in the figure indecate means (dot) } SE(bar).*p<0.05,**p<0.01

Fig. 3 Correlations between changes in heart rate (HR) and plethysmogram wave height (WH), HR and coefficients of variations of R-R intervals in ECG ( CVRR), and WH and CVwx in the gum chewing and control experiments. Symbol ( ) indicates differences from resting values in preexperiment.

Fig. 4 Correlations between changes in plethysmogram wave height (WH) and plasma nor-adrenaline (pnorad), heart rate ( HR) and adrenalinne ( Ad), coefficients of variations of wave height (CVwx) and blood lactate (LA) concentration, and HR and pnorad concentration in the gum chewing and control experiments. Symbol ( ) indicates differences from resting values in pre-experiment.

Function of sympathetic and parasympathetic nerves during gum chewing With CVRR, wave Height of plethysmogram and plasma catecholamine concentration as functional indices of autonomic nerves Ikuo ISHIYAMA1), Masato SUZUKI2), Shigeru MATSUBARA3), Toshio TAKIGUCHI4), Shozo KUDO4), Yoshihisa SUZUKI4) and Yoshinori SATO4) 1) Physical Education Laboratory, Tochigi Jr. College, Kodugakuin University. 2) Department of Laboratory Medicine, Jikei-kai University. School of Medicine. 3) Faculty of Pharmacy, Nihon University. 4) Chewing Gum Dept. Lotte Central Laboratory Co., Ltd. Abstract: The present study examined the changes in heart rate (HR), coefficient of variation of ECG R-R intervals (CVRR), plethysmogram (PTG) wave heigth (WH) and CV (CVWH), plasma catecholamine (pad, pnorad), blood sugar (BS), immuno-reactive insulin (IRI) and lactate (LA) associated with gum chewing, and considered the function of autonomic nerves during gum chewing. Eleven healthy male volunteers (24.5 ± 4.1yr.) chewed three kinds of gum which consisted of three different levels of hardness. During gum chewing in the supine position, HR increased 10-40 bpm,c VRR decreased from the resting value, and CVRR increased immediately after chewing stopped. WH decreased during gum chewing, and remained lower than the resting WH value after chewing stopped VWH increased during gum chwing. Catecholamine was detected in higher concentrations after gum,c chewing than at rest. Moreover, pnorad was at a higher concentration, and the BS, IRI and LA concentrations rose above the values at rest until 10 minute after all gum chewing ended. In addition, we observed a significant negative correlation between pad and CVRR, WH and CVWH in gum chewing exericse. These findings suggested that sympathetic nerve activity was enhanced during gum chewing, and that parasympathetic nerve activity was enhanced and sympathetic nerve activity remained enhancing slightly after gum chewing stopped. Key words: Gum chewing, Sympathetic and Parasympathetic Nerve, CVRR, Wave height of Plethysmogram, Plasma Catecholamine Concentration