Arteriolar vasomotion: implications for tissue ischemia.

Vasomotion, the rhythmical contraction and relaxation of the arterioles, is a natural property of the arteriolar microcirculation. It is observed clinically through related flow variations (flux motion) which are detected by laser Doppler flowmetry. It presents two distinct regimens: slow and fast waves, with frequencies of 1-2 and 10-20 cpm, respectively. Both activities are found in normal tissues, and their rate of incidence as well as their magnitude become significantly enhanced during abnormal conditions associated with low blood pressure and hypoperfusion. The institution of this activity by abnormal tissue conditions suggests that vasomotion is a reaction of the microcirculation aimed at improving microvascular function.