A novel apparatus for non-invasive,in vivo evaluation of arterial mechanical properties was developed.A rigid airtight chamber with an ultrasound probe was attached to the upper arm to manipulate transmural pressure(TP) of the brachial artery by changing the pressure in the chamber.Pressure-diameter relationship of the brachial artery was obtained by measuring the diameter with the probe while pressurizing and depressurizing the chamber.Pressure-diameter relationship of the brachial artery could be obtained reproducibly over a wide range of TP.Myogenic response of smooth muscle cells was evaluated by hysteresis area of the pressure-diameter curves.This apparatus may be useful to measure not only pressure-diameter relationship as a mechanical property of artery but also contractility of smooth muscle cell.
