Platelet activation during hand vibration.

The level of beta-thromboglobulin, the circulating platelet aggregate ratio and platelet sensitivity to aggregation with adenosine 5'-diphosphate (ADP) and collagen were assessed in 12 control subjects, 16 patients with vibration white finger (VWF) and 15 patients with primary Raynaud's disease; this was done before and after a 1-min exposure to hand vibration. The beta-thromboglobulin level increased significantly in controls, from a median (interquartile range) of 35.5 (22-47) to 47.5 (27-52) ng/ml, and in the VWF group from 44.0 (39-60) to 47.5 (42-109) ng/ml (P < 0.005). Vibration had no effect on circulating platelet aggregate ratio in any group. The platelets of normal subjects tended to be more sensitive to aggregation with low-dose ADP (1 mmol/l) than those of patients with VWF or primary Raynaud's disease. Significant change occurred in the lag phase of the aggregation response to vibration in the control group at an ADP concentration of 2 and 5 mmol/l. These results indicate that intravascular platelet aggregation occurs as a result of exposure to vibration. Platelet sensitivity to aggregation with ADP may be decreased in patients with VWF or established Raynaud's disease.