The Relationship between the Ambulatory Variability and the Laboratory Reactivity of Blood Pressure and Heart Rate.

We examined the relationship between the ambulatory variability and the laboratory reactivity of systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) in 21 male college students. The mean increase during the waking period from that during sleep was defined as variability 1, and the standard deviation of the ambulatory measurements during waking was defined as variability 2. The reactivity to laboratory tests was measured by the pretask-to-task increase in variables. The high SBP variability 1 group showed a significantly higher reactivity of SBP and noradrenaline in the bicycle exercise test (70w). This suggests the possibility that SBP variability 1, can be predicted by increased reactivity to a mild limb exercise test. The high HR variability 1 group, and the high SBP variability 2 group showed significantly lower reactivity of stroke volume (SV) and cardiac output (CO) in the cold face test. Thus, parasympathetic responses such as trigeminal-brainstem-vagal pathway function or baroreflex sensitivity seemed to be reduced in these groups. The high DBP variability 2 group showed significantly lower DBP reactivity in the cold face test, and low noradrenaline reactivity in the mental arithmetic test, which indicated a reduced alpha-adrenergic response in this group. No other significant differences in reactivity to the laboratory mental stress tests were found between the variability 1 and variability 2 groups.