Assessment of training effects on autonomic modulation of the cardiovascular system in mature rats using power spectral analysis of heart rate variability.

OBJECTIVE: To clarify the effects of forced or voluntary exercise on autonomic modulation of the cardiovascular system, we monitored changes in autonomic nervous activity in a mature rat by spectral analysis of the heart rate (HR) during a 10-week training period. METHODS: Male Wistar rats implanted with a radio-telemetry system were divided into three groups at 18 weeks of age: (1) Control group (n = 8); (2) Voluntary group (n = 6), which were housed separately in a cage with a running wheel; (3) Forced group (n = 6), which were exercised on a treadmill (35 m/min, 15 min/day, 5 days/week). The electrocardiogram was analyzed by the maximum entropy method into two main oscillations, low-frequency (LF) and high-frequency (HF) oscillations, respectively. LF and HF are considered to be markers of both sympathetic and parasympathetic modulations and parasympathetic modulation, respectively. RESULTS: Average running distances of the Voluntary group were more than twofold higher than those of the Forced group. HR levels in the Forced group were lower than those in the Control group. LF and HF levels in the Control and the Forced groups were almost the same during the experiment, and those in the Voluntary group showed a tendency to decrease. CONCLUSION: The results in the Voluntary and the Forced groups suggest that cardiovascular adjustments are not simply caused by the quantity of exercise. In the Voluntary group, both sympathetic and parasympathetic activity may decrease with a predominance of sympathetic activity. Conversely, in the Forced group, the baroreflex may be hyper-activated by the undesired treadmill running and handling stress.

Assessment of training effects on activity levels of alveolar macrophage in matured rats using chemiluminescent technique.

Chemiluminescence responses have been used for the evaluation of phagocyte function. In this study, to evaluate effects of training started after maturation on pulmonary immunity, the activity levels of rat alveolar macrophages (AMs) were assessed as reactive oxygen species (ROS) generating capacity, measured by lucigenin- and luminol-dependent chemiluminescence, using a parallel luminometer. One group of male Wistar rats started training at 11 weeks old and another group at 17 weeks old. The experimental period was 12 weeks, and about half of the rats were sacrificed after 6 weeks. The forced and voluntary exercises affect the mean levels of body weights and cell populations in the bronchoalveolar lavage fluid in younger animals; however, the voluntary exercise group in younger animals seemed to adapt after 12 weeks. By contrast, chemiluminescence responses in older rats observed after 6 weeks suggest that AMs are primed, and the maximum releasing activities of ROS are reduced. These changes in AM activity may be caused by the exercise and separation stresses and the rats may adapt to those stressors after 12 weeks. The chemiluminescent technique is thought to be useful to evaluate the changes of AM activity.