The effect of acute and chronic femoral artery ligation on the blood flow through the gastrocnemius muscle of the rat examined using laser Doppler flowmetry and xenon-133 clearance.

In this investigation the resting gastrocnemius muscle blood flow of the anaesthetized rat was evaluated using a recently developed laser Doppler flowmeter and the xenon-133 clearance technique. The perfusion of the microvasculature of the muscle was measured in normal control rats and in animals in which the supplying femoral artery had been acutely (1 h-1 week) or chronically (8-12 weeks) ligated. The laser Doppler flowmeter allowed continuous measurements of the muscle perfusion. Such measurements revealed a rhythmic fluctuation in the perfusion of the gastrocnemius muscle. The xenon-133 clearance technique did not allow continuous recording of muscle blood flow and rhythmical flow changes could not be observed. Acute ligation of the femoral artery reduced the mean muscle perfusion by 41% and 52% when assessed by laser Doppler flowmetry and xenon-133 clearance respectively. In comparison to animals without femoral artery ligation the hyperaemic response, following release of a tourniquet around the thigh or of an abdominal aortic occlusion, was markedly attenuated. Chronic ligation of the femoral artery reduced the mean muscle perfusion by 33% and 32% when assessed by laser Doppler flowmetry and xenon-133 clearance respectively. In these animals the hyperaemia, following tourniquet-induced muscle ischaemia, was reduced, compared to normal animals, but was more pronounced than observed in acutely ligated animals. In the chronically ligated animals abdominal aortic occlusion did not produce sustained muscle ischaemia and consequently no hyperaemic response was observed upon release of the aortic occlusion. We conclude that, as judged by the comparability of the results obtained using xenon-133 clearance, the laser Doppler flowmeter is a useful and sensitive new tool for the examination of the perfusion of tissue blood flow. The results suggest that chronic ligation of the rat femoral artery induces circulatory changes which mimic those seen in claudicants.