The input impedance of the peripheral vascular termination in skeletal muscle

In order to investigate the dynamic behaviour of the peripheral vessels of the arterial system, simultaneous pressure-flow measurements were made in the deep femoral artery of the rabbit at the same site. The input impedance calculated from the recorded pulses was regarded as representing the peripheral vascular termination in skeletal muscle and was expressed in terms of modulus and phase. The modulus decreases monotonously with increasing frequency while the phase angle is about −45° in the low frequency range and becomes less negative with increasing frequency. This behaviour can be simulated by a model in which the inert mass of the pulsating blood, the elastic compliance of the blood vessels, and the frictional resistance to blood flow are taken into account. An essential result is that the model is provided with a considerable degree of elastic compliance, which means that the peripheral vessels as a whole possess an important compliance and do not behave like pure frictional resistances.