An investigation on the biodynamic foundation of a rat tail vibration model

Abstract

The objectives of this study are to examine the fundamental characteristics of the biodynamic responses of a rat tail to vibration and to compare them with those of human fingers. Vibration transmission through tails exposed to three vibration magnitudes (1 g, 5 g, and 10 g r.m.s.) at six frequencies (32 Hz, 63 Hz, 125 Hz, 160 Hz, 250 Hz, and 500 Hz) was measured using a laser vibrometer. A mechanical-equivalent model of the tail was established on the basis of the transmissibility data, which was used to estimate the biodynamic deformation and vibration power absorption at several representative locations on the tail. They were compared with those derived from a mechanical-equivalent model of human fingers reported in the literature. This study found that, similar to human fingers, the biodynamic responses of the rat tail depends on the vibration magnitude, frequency, and measurement location. With the restraint method used in this study, the natural frequency of the rat tail is in the range 161-368 Hz, which is mostly within the general range of human finger resonant frequencies (100-350 Hz). However, the damping ratios of the rat tail at the unconstrained locations are from 0.094 to 0.394, which are lower than those of human fingers (0.708-0.725). Whereas the biodynamic responses of human fingers at frequencies lower than 100 Hz could be significantly influenced by the biodynamics of the entire hand-arm system, the rat tail biodynamic responses can be considered independent of the rat body in the frequency range used in this study. Based on these findings it is concluded that, although there are some differences between the frequency dependences of the biodynamic responses of the rat tail and human fingers, the rat tail model can provide a practical and reasonable approach to examine the relationships between the biodynamic and biological responses at midrange to high frequencies, and to understand the mechanisms underlying vibration-induced finger disorders.

Increased Oxidant Activity Mediates Vascular Dysfunction in Vibration Injury

“…In the rat paw and digits, transmissibility was also at or slightly above 1.0, between 63 and 250 Hz. Transmissibility in the rat paw was less than that observed in human fingers (Dong et al, 2005b) or rat tails (Welcome et al, 2008), which may be explained by their differences in mass and stiffness. However, the results demonstrate that the paw model can be used to study the effects of vibration and provide mechanistic insight into how vibration causes pathological changes in the hand-arm system.…”

Vibration Disrupts Vascular Function in a Model of Metabolic Syndrome

“…We chose this frequency and acceleration because many tools, including grinders, cement saws and chipping hammers, display vibration characteristics at or above this frequency. We also chose these vibration parameters because previous work in our laboratory has demonstrated that the biodynamic response of the rat tail is similar to the response of the human fingers at this frequency and acceleration 17) . Control rats were treated in an identical manner except that their tails were secured to a non-vibrating platform mounted onto isolation blocks.…”

“…The remaining, distal portion of the tail was also collected, placed into cold Dulbeccos modified Eagle's medium (DMEM; Invitrogen; Carlsbad, CA, USA), and stored at 4˚C for in vitro analyses of vascular function as described below. Arteries were dissected from these specific regions of the tail because the physical stress and strain of vibration is greatest in regions between the strap restraints 17) and these regions display altered vascular responses after exposure to a single bout of vibration 14) .…”

“…These results suggest that the effects of vibration on the peripheral vascular system are in part due to an organism's physiological response to vibration, and are not solely a result of the direct effects of vibration on the tissue. However, data collected in rats 17,32,33) and in humans 21,34,35) have demonstrated that both the shear and bending stresses of soft tissues, and the responses of the vascular system to vibration, are frequency and amplitude dependent. These data indicate that vibration also has some direct effects on vascular function.…”

Characterization of Frequency-Dependent Responses of the Vascular System to Repetitive Vibration

“…The goal of this study was to use a rat tail model characterized in our laboratory 12 to examine the frequency-dependent responses of sensorineural function, peripheral nerves, and sensory neurons in the dorsal root ganglia (DRG) to vibration. We have previously used this model to characterize frequency-dependent changes in vascular function and identify some of the mechanisms that may underlie these changes.…”