Hemodynamic changes in skin microcirculation induced by vibration stress in the conscious rabbit.
Cutaneous microcirculatory responses to vibration stress were observed by microphotoelectric plethysmography in a transparent round window installed in the ears of conscious rabbits. Vertical vibrations at frequencies ranging from 8 to 250 Hz were applied to the abdomen of the rabbits for 5 min. The vibrations produced an increase in heart rate and the index of discomfort, and a decrease in blood flow in the skin microcirculation. The maximum response was observed at 63 Hz. Rhythmic fluctuations in microcirculation were associated with two components: component A had a small amplitude and high frequency, and component B had a large amplitude and low frequency. Vibration exposure led to a large increase in component B and a smaller increase in component A. During vibration exposure, component A was suppressed by treatment with diltiazem, a calcium channel blocker, and was not affected by bunazosin, an alpha-1 adrenoceptor antagonist. The opposite changes were observed for component B. This indicates that components A and B of the rhythmic fluctuations are regulated by myogenic and neurogenic activities, respectively. Thus, the hemodynamic changes of skin microcirculation induced by vibration may actually be due to a neurogenic factor, especially sympathetic nerve activity. The responses appear to depend on the frequency of the vibrations.
Ishitake
T
T
Department of Environmental Medicine, Kurume University School of Medicine, Japan.
D000818:Animals; D006439:Hemodynamics / Q000502:physiology; D008297:Male; D008833:Microcirculation / Q000502:physiology; D011817:Rabbits; D012867:Skin / Q000098:blood supply*; D013312:Stress, Physiological / Q000503:physiopathology*; D014732:Vibration / Q000009:adverse effects*