Background: The aim was to evaluate the interactions between the effects of vagal stimulation by sham feeding (nonbaroreflex) and deep breathing (baroreflex) on heart rate variability (HRV) and gastric myoelectrical activity (GMA) in pre- and postmenopausal women with essential hypertension.
Material/Methods: One hundred five post- and premenopausal women with hypertension and 60 premenopausal normotensive women were observed. The study protocol consisted of 5 min of resting HRV followed by 5 min of deep breathing (DB), then 6 min of sham feeding (SF) with 30-min electrogastrography (EGG) before and after SF. The fasting plasma level of noradrenalin was measured.
Results: The HRV parameter values at rest in the hypertensive group were half those in the control group (p<0.05). There were notably higher HRV parameter values in the premenopausal women. Plasma noradrenalin level was higher in the postmenopausal women (p=0.0009). The effect of DB was similar before and after menopause; however, HRV parameters in response to DB were lower in the hypertensive women than in the controls (p<0.05). In the controls there was a marked increase in the main HRV parameters in response to DB. In fasting electrogastrography the lowest normogastria percentage was observed in the postmenopausal women. EGG showed that only SF significantly affected the period dominant power (PDP) in all groups and the bradygastria percentage in the postmenopausal women.
Conclusions: This study suggests that the interactions that occur between the effects of non-baroreflex and baroreflex vagal stimulation in hypertensive women may contribute to gastric motility disorders and dyspeptic symptoms.

Keywords: vagal stimulation, essential hypertension, Autonomic Nervous System, heart rate variability, electrogastrography, Premenopausal, postmenopausal, Electromyography, Electrophysiological Phenomena - physiology, Fasting - physiology, Feeding Behavior - physiology, Heart - physiopathology, Heart Rate - physiology, Hypertension - physiopathology, Norepinephrine - blood, Physical Stimulation, Respiration, Stomach - physiopathology, Time Factors, Vagus Nerve - physiopathology