Frequency dependence of the suppressive effects of vibration on atherosclerosis in the rabbit

Whole-body vibration suppresses the development of atherosclerosis in the rabbit (Oki and Matoba, 1987). The present study was designed to clarify whether the effect of vibration on atherosclerosis depends on the frequency of vibration. Longitudinal vibrations at a frequency of 30 or 60 Hz was applied to 12 New Zealand white rabbits for 12 weeks. The gradual decrease in body weight and blood hematocrit in the vibration groups with time were parallel to the changes in the controls. The rate of increase in serum lipid concentrations induced by a cholesterol-rich diet was significantly suppressed in the vibration groups, as compared to the controls. This may be due to the vibration and not the diet. The aortic wall was thinner at 60 Hz than at 30 Hz, whereas the ratios of trace metals (Ca/Mg and Zn/Cu) in the aortic tissues were smaller at 30 Hz. The area of plaque formation in the intima was smaller at 60 Hz than at 30 Hz (p less than 0.05). Thus, the suppressive effect of vibration on the development of atherosclerosis in the aorta may be greater at a frequency of 60 Hz than at 30 Hz. Vibration may play an important role in lipid metabolism.