Use of the Isolated Perfused Arterial Segment for Studying Properties of Vascular Smooth Muscle

Abstract

No preparation is completely objection-free for obtaining results which describe completely and accurately the responses of vascular smooth muscle to stimulation by mechanical forces, nerve stimulation and/or vasoactive hormones. We believe that the isolated perfused segment of a leg artery as we use it offers opportunities for more straightforward and relevant observation and interpretation than many others. The actual hydraulic system in which pressure and flow are being observed can be clearly defined, and the segment is normally tethered and has its normal innervation. Flow can be uncontrolled by the use of existing arterial pressure or kept constant by a proper pump. In the constant flow mode, pressure levels and gradients can be controlled by suitable combinations of clamps and gates. Arterial branches must be avoided; vasa vasorum are a necessary but usually negligible complication. Stimulations are applied either at a small nerve just proximal to the arterial segment or on the distal stump of a crushed sciatic nerve in the presence of succinyl choline. Responses are quantitated in terms of resistance changes of the segment. Under these circumstances we have studied the effects of frequency and duration of stimulus trains, resting intervals, initial stretch, and the interactions of these parameters. We are setting up our equipment for direct photographic recordings to facilitate quantitative estimates of wall tensions.

This research has been supported by grants from the Georgia Heart Association and the USPHS, Grant HE-00240.