Structure and function of small arteries

The small arteries (prearteriolar vessels with lumen diameter less than approximately 500 microns) contribute importantly to and participate actively in the regulation of the peripheral resistance. New techniques, building on the classic histological and hemodynamic techniques, have enabled detailed in vitro investigation of small arteries. At present, research in small arteries is in its infancy, and our understanding of the heterogeneity of small arteries within vascular beds, between vascular beds, and between species is extremely limited. This review attempts to describe the current status of the field. New techniques, based primarily on a wire myograph (where the vessels are mounted as ring preparations) and a pressure myograph (where vessels are cannulated and pressure-lumen relations are determined), have allowed in vitro investigations of small arteries. The more physiological arrangement of the pressure myograph allows, for example, investigation of the vasoconstrictor response to raised intravas...