Effect of vibration on the activity of the plasma kallikrein-kinin system in the rat.

Rats were exposed to whole body vibration horizontally for four hours at 5 Hz frequency and 2 cm amplitude. Of the components of the plasma kallikrein-kinin system the free (spontaneous) and kaolin-activated kallikrein (prekallikrein) activities, the concentration of bradykinin, the bradykinin splitting total kininase activity, total kallikrein-inhibitor activity and the concentration of alpha 2-macroglobulin, a major plasma kallikrein inhibitor, were estimated. Results showed that in response to acute vibration plasma free kallikrein activity was increased significantly in association with a significant reduction of prekallikrein concentration. The concentrations of bradykinin and total kininase activity were significantly elevated, too. Neither total kallikrein-inhibitor activity nor the concentration of alpha 2-macroglobulin were changed indicating that the plasma kallikrein inhibitors did not play a role in the alterations of plasma free kallikrein and prekallikrein activities. During acute vibration the plasma kallikrein-kinin system was activated probably by the enhanced catecholamine secretion. We suggest that the biological importance of this phenomenon is in the defense against the impaired microcirculation caused by catecholamines.