Myogenic responses of isolated rat skeletal muscle venules: modulation by norepinephrine and endothelium

The role of epinephrine and endothelium in pressure-sensitive myogenic response in skeletal muscle venules were investigated using first-order venules of rat gracilis muscle. The venules showed increases in diameter in response to perfusion pressure (PP). In passive conditions, the pressure-diameter curve shifted upwards, but shifted downwards in the presence of norepinephrine (NE). The removal of endothelium caused a marked decrease in venular diameters. These results suggest that NE is involved in the regulation of myogenic tone in rat skeletal muscle.