Effect Of Hind Legs Vibration On Endothelial Cells' Incretion Function And Expression Of Apoptosis-Related Gene

ObjectiveProlonged exposure to vibration from hand-held power tools and vibrating machines may cause debilitating vascular and neural dysfunction in humans, which may be the pathophysiology of hand-arm vibration syndrome.Increased of the endothelium-derived constricting factor and descerased of endothelium-derived relaxing factor induced by vibration may contribute to digital vasospasms , moreover, sympathetic hyperactivity has also been found in patients of HAVS; but the onset and progression of the disease is poorly understood.The purpose of the study was to elucidate the relationship between the change of ET, TXA2 and IL-8 level and the mechanism of vibration-induced vascular impairment,and the effects of local vibration on endothelial cell apoptosis.To study the dose-effect relationship between local vibration and the level of IL-8,ET and TXA ₂ and expression of Bcl-2 and Bax.Methods1.32 rabbits were divided into four groups at random .Three groups(A group ,B group and C group )were tested by different vibration power and one was normal control group. Plasma levels of ET, TXA2 and serum level of IL-8 were measured with radioimmunoassay.2. After the vibration test, hind leg muscle samples were selected from the A, C and D group after the 24 rabbits in the three groups were killed. SABC immunohisto- chemistry was used to detect the expression of Bax and Bcl-2 in the vascularendothelial cells.Results1. The level of ET and TXA₂ showed an increasing trend with the increase of vibration length and intensity. ET and TXA₂ were higher in all experimental groups after vibration test than that in control group; Howervr.the IL-8 concertration in the three vibration groups were significantly decreased than that in the controls.2. Light microscopy showed irregular proliferation in the tunica intima and tunica media, especially in the former; proliferation of febrous connective tissue and degeneration of partial tissues and infiltration of inflammatory cells were observed in the vibration group. Bax expression was significantly higher than that in the normal controls, and Bcl-2/ Bax ratio of the cells in the vibration group was significantly lower than that in the controls.Conclusions1 .Local vibration may cause the plasma levels of ET,TXA2 increase and serum level of IL-8 decrease,and these trend were more apparent with the vibration intensity higher.the changes of these endothelium factor might be one of the mechanisms of the vibration-induced vascular impairment.2.Local vibration may cause the endothelial cell apoptosis.Time and intensity-dependent change of the endothelial cell apoptosis occur which may induce the damage of the blood vessal integrity; the endothelial cell apoptosis may affect its incretion function which may induce the vibration-induced vascular impairment.3. After the test,light microscopy showed damage of endothelial cell and irregular proliferation in the smooth muscle and tunica media.Obstruction of the blood vessel and infiltration of inflammatory cells and thrombosis attached to the intima were observed,which may be one of the aetiological agent of hand arm vibration disease.