Isometric rings and normal conduit arterial contractions cannot predict stenotic responses: a unique vascular contraction within a stenosis

Because in a stenosis the contraction is neither isometric nor isotonic, studies examining isometric rings or normal conduit arterial contractions may not predict stenotic hemodynamic responses. To investigate this question, we compared responses in stenotic arteries and in isometric arterial rings and normal conduit arteries to basic interventions–constriction, dilation, and denudation. Canine carotid arteries were isolated and perfused with a physiologic salt solution under constant pressure (100 mm Hg) and with a fixed distal resistance. After creating an intraluminal stenosis, proximal and distal pressures, flow, and arterial dimensions were continuously recorded as norepinephrine was added to the perfusate. The stenotic diameter shortened significantly more than the proximal diameter (1.2±2 mm vs 0.5±0.1 mm, P