Comparison of continuous and intermittent vibration effects on rat-tail artery and nerve.

Hand-transmitted vibration from powered-tools can cause peripheral vasospasm and neuropathy. A rat-tail model was used to investigate whether the pattern of vibration influenced the type and severity of tissue damage. The tails of awake rats were vibrated continuously or intermittently for a total of 4 hours at 60 HZ, 49 m/s(2). Nerves and arteries were harvested immediately or 24 hours after treatment. Tails subjected to intermittent vibration showed transiently increased sensitivity to thermal stimuli. Intermittent vibration caused the most nerve injury immediately and 24 hours after vibration. Continuous vibration invoked a persistent reduction in vascular lumen size. Compared to epinephrine-induced transient vacuolation in vascular smooth muscle cells, both continuous and intermittent vibration caused greater persistence of vacuoles, indicating a vibration-induced pathological process. All vibration groups exhibited elevated nitrotyrosine immunoreactivity indicative of free-radical damage. Pattern of vibration exposure may exert a major influence on the type of vibration injury.