Relationship between Passive and Active Pulsations of Rat Artery as Vascular Extension of Frank—Starling Law

The experiments on narcotized male rats ( n =30) determined the parameters of passive and active pulsatile modes of isolated segment of femoral artery in situ . Rheographic elasticity (RE) and reactivity (RR) were correspondingly determined as the ratios of peak-to-peak (p2p) magnitudes of passive and active pulsatile oscillations of arterial electroimpedance (AEI) to p2p magnitude of BP undulations. The medians and interquartile ranges of RE and RR were 6 (3; 11) and 70 (40; 110) mΩ/mm Hg, respectively. The maximal and minimal values of RE and RR in various rats differed by 50 and 80 times, respectively, and were bimodally distributed: in major group ( n =23), the values were RE300 mΩ/mm Hg. The above ranges of RE and RR parameters were considered as the diagnostic signs of normal and pseudo-healthy rats with pathologically augmented AEI oscillations, respectively. Statistical analysis of all rats ( n =30) revealed the positive correlation between RE and RR ( r =0.76) with linear regression RR=31+7.6×RE. It is hypothesized that this correlation is underlain by a mechanism similar to that described by the Frank—Starling law for myocardium.