Changes of diameter and length in cylindrical segments of canine femoral arteries during activation at different pressures.

Changes in diameter and length of cylindrical segments of canine femoral arteries were recorded at different transmural pressures, and these dimensional changes have been compared with those of rings and longitudinal strips of the vessel wall. The segments responded to stimulation (noradrenaline or 40 mmol/l of potassium) with a reduction of the diameter at all transmural pressures applied. The length of the segments increased during stimulation when the transmural pressure was zero, but decreased at higher transmural pressures (60-70 mm Hg). This shortening at normal transmural pressure was converted to a small lengthening when the segment was stretched to in situ length. The factors determining these responses are discussed.