The Effects of Hindlimb Unloading of Rats on Rheographic Parameters of Femoral and Brachial Arteries In Situ

The rheographic parameters of the segments of brachial and femoral arteries were measured in situ after a 14-day-long hindlimb unloading (HU) of rats. HU significantly increased electrical impedance Z of a segment of femoral artery indicating its constriction; in parallel, HU resulted in a decreasing trend of Z of a segment of brachial artery attesting to its dilation. In both arteries, HU significantly or as a trend decreased the swing ranges of active and passive pulsations, respectively. BP reduction during bloodletting induced transition from passive to active pulsatile mode in the femoral artery only in 33% experimental rats in contrast to 87% control ones. We suppose that degradation of active pulsatile mode is responsible for the negative influences of microgravity and weightlessness on blood circulation. The study determined the rheographic parameters that reliably reflect changes in the functional activity of arteries after chronic redistribution of hydrostatic load.