Effect of acute ischaemia on active and passive large deformation mechanics of canine carotid arteries.

Large deformation mechanical properties of dog carotid arteries excised following 1 hour of ischaemia and 1 hour of reperfusion were compared to those of contralaterial normal arteries in vitro. Vascular smooth muscle was invariably activated by 0.5 microgram/ml noradrenaline. Relative reduction in the diameter of postischaemia arteries following noradrenaline administration was twice as large (max.: 13.2 +/- 2.0%) as that of normal controls (max.: 5.7 +/- 1.5%) in the pressure range of 0--220 mmHg. If the smooth muscle was totally relaxed there were no differences between the geometrical (wall-thickness, radius) and mechanical properties (stress, incremental elastic modulus, incremental distensibility, strain-energy density) of the arteries in the two series. It is concluded that the increased reactivity of postischaemic arteries is not caused by changes in geometric or mechanical properties of their passive wall elements.