Nifedipine pretreatment reduces vibration-induced vascular damage

A rat-tail vibration model of hand-arm vibration was employed to test whether preemptive administration of nifedipine (5 mg/kg) to block vasoconstriction prevents vibration-induced arterial damage. The tails of vibrated and nifedipine-pretreated vibrated Sprague-Dawley rats were exposed continuously to 4 h of 60-HZ vibration at 49 m/s(2) rms. In nonvibrated anesthetized rats, the ventral tail arteries were bathed for 15 min in situ in 1 mM epinephrine or 1 mM norepinephrine to induce structural changes indicative of intense vasoconstriction. Arteries were processed for light and electron microscopy 45 min after treatment. Compared to sham control, 4-h vibration significantly (P < 0.01) reduced lumen size, generated endothelial disruption (7.0 +/- 2.6%), elevated nuclear factor of activated T cells c3 (NFATc3) expression in endothelial and smooth muscle cells, and increased smooth muscle cell vacuolization. The findings demonstrate that blockage of vibration-induced vasoconstriction with nifedipine prevents acute vascular damage. Smooth muscle and endothelial cells structurally altered by vasoconstriction are rendered susceptible to damage by vibration.