PURPOSE: Intravascular interventions such as balloon embolectomy lead to endothelial injury. The extent and functional consequences of this endothelial injury are not known. METHODS: Segments of bovine carotid artery were equilibrated in a vasomotor perfusion apparatus (VPA). Smooth muscle function was determined by the contractile responses to 10(-5) M norepinephrine (NE). Endothelial function was evaluated by the extent of vasorelaxation to the subsequent addition of 10(-5) M acetylcholine (ACh). To determine the pattern of injury throughout the length of the vessel, strips of artery from along the vessel length were also evaluated in a muscle bath. Morphology was examined by scanning electron microscopy (SEM). RESULTS: No significant differences were noted in the contractile response to NE after embolectomy. Balloon embolectomy significantly decreased the relaxation response to ACh from 97 +/- 1% before embolectomy to 89 +/- 1% after embolectomy (n = 5 vessels, P < 0.01, ANOVA). In the muscle bath, the vasorelaxation of strips precontracted with NE was variable throughout the length of the vessel suggesting that endothelial injury was diffuse. The relaxation response to ACh was inhibited by L-NMMA. SEM revealed patchy areas of endothelial denudation. CONCLUSION: Embolectomy produces no change in smooth muscle function and partial injury to the endothelium in intact vessels. However, there remains sufficient endothelial function after balloon embolectomy to produce NO-dependent vasorelaxation and modulate vasomotor tone.
PURPOSE: Intravascular interventions such as balloon embolectomy lead to endothelial injury. The extent and functional consequences of this endothelial injury are not known. METHODS: Segments of bovine carotid artery were equilibrated in a vasomotor perfusion apparatus (VPA). Smooth muscle function was determined by the contractile responses to 10(-5) M norepinephrine (NE). Endothelial function was evaluated by the extent of vasorelaxation to the subsequent addition of 10(-5) M acetylcholine (ACh). To determine the pattern of injury throughout the length of the vessel, strips of artery from along the vessel length were also evaluated in a muscle bath. Morphology was examined by scanning electron microscopy (SEM). RESULTS: No significant differences were noted in the contractile response to NE after embolectomy. Balloon embolectomy significantly decreased the relaxation response to ACh from 97 +/- 1% before embolectomy to 89 +/- 1% after embolectomy (n = 5 vessels, P < 0.01, ANOVA). In the muscle bath, the vasorelaxation of strips precontracted with NE was variable throughout the length of the vessel suggesting that endothelial injury was diffuse. The relaxation response to ACh was inhibited by L-NMMA. SEM revealed patchy areas of endothelial denudation. CONCLUSION: Embolectomy produces no change in smooth muscle function and partial injury to the endothelium in intact vessels. However, there remains sufficient endothelial function after balloon embolectomy to produce NO-dependent vasorelaxation and modulate vasomotor tone.