Applied force alters sensorineural and peripheral vascular function in an animal model of hand-arm vibration syndrome

Updated March 11, 2024

March 2024

NIOSH Dataset RD-1080-2024-0

Introduction

Working with vibrating hand tools is associated with the development of hand-arm vibration syndrome (HAVS). HAVS is characterized by cold-induced vasospasms, finger blanching and changes in sensory function. Vibration plays a major role in the development of the symptoms that are characteristic of HAVS, however, the hands and fingers of worker using tools are also exposed to pressure applied as the workers grip tools. The pressure applied by gripping a tool might also affect blood flow and sensorineural function. Therefore, this study examined the effects of applied pressure [2 and 4 newtons (N)] on peripheral vascular and sensorineural function using a characterized rat tail model. The tails of rats were exposed to 0, 2 or 4N of applied force for 10 days. Blood flow (laser doppler) and sensitivity of the tail to pressure (Randall-Selitto pressure test) was measured on days 1, 5 and 10 of the exposure. The sensitivity of the tail nerves to electrical stimulation was measured on days 2 and 9.

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Methods Collection

Pathogen free male (n=18 or 6 animals/group) Sprague-Dawley rats (H1a: (SD) CVF, approximate body weight of 200 – 230 g at arrival), were obtained from Hilltop Lab Animals, Inc. (Scottdale, PA).
Animals were acclimated to AAALAC International accredited animal facilities at NIOSH for one week.
The exposure and all other procedures performed were approved by the Institutional Animal Care and Use Committee and were in compliance with the Public Health Service Policy on Humane Care and Use of Laboratory Animals and the NIH Guide for the Care and Use of Laboratory Animals.
After acclimation to the facilities, animals were acclimated to restraint for 5 d.
On day 1 of the experiment, the tails of animals were exposed to 2 or 4 N of applied force for 4 h/day for 10 consecutive days. Control animals were placed in a restrainer but their tails were not exposed to pressure.
Laser doppler measurements of blood flow, and sensitivity to pressure using the Randall-Selitto test were made pre- and post-exposure on days 1, 5 and 10 of the experiment.
Sensory nerve function was measured the day prior to the beginning of the exposure, and pre- and post-exposure on days2 and 9 of the study.
Animals were euthanized the morning following the last exposure.
For microvessel measurements, tails were dissected from rats after exsanguination and placed in cold Dulbecco’s modified Eagle’s medium with glucose (Invitrogen/Gibco; Carlsbad, CA). The ventral tail artery was dissected, mounted in a microvessel chamber, and vasoconstriction to increasing concentrations of phenylephrine and vasodilation to increasing concentrations of acetylcholine were measured
Other tissues collected were frozen in cryotubes and included the ventral tail artery and nerves, the dorsal root ganglia, the spinal cord and the brain. Tissues were stored at -80ºC until processed.

Citations-Publications based on this dataset:

Krajnak, K., Warren, C, Xu, X., Chapman, P., Waugh, S., Boots, T., Welcome, D., Dong, R. (2024). Effects of applied pressure on sensorineural and peripheral vascular function in an animal model of hand-arm vibration syndrome. Journal of Environmental and Occupational Medicine. 66:93-104.

Acknowledgements

This work was supported by NORA grant (9390KK1) to K. Krajnak, National Institute for Occupational Safety and Health.

Kristine Krajnak                     ksk1@cdc.gov
Christopher Warren                cpw4@cdc.gov
Sherry Xu                               fze2@cdc.gov
Phillip Chapman                     ttf4@cdc.gov
Stacey Waugh                         ztz6@cdc.gov
Theresa Boots                         oph6@cdc.gov
Daniel Welcome                     zzw8@cdc.gov
Ren Dong rkd6@cdc.gov

Contact

For further information contact:

Physical Effects Research Branch (PERB),
Health Effects Laboratory Division (HELD),
National Institute for Occupational Safety and Health (NIOSH), Morgantown, WV.

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