Prostaglandins in the control of blood flow in canine skeletal muscle.

Abstract

SUMMARY1. The effects of systemic hypoxia, arterial occlusion and muscle exercise on blood flow and oxygen uptake of the hind limb of anaesthetized areflexic dogs were assessed. The control responses were compared to those elicited after administration of meclofenamic acid (2 mg/kg, i.v.).2. Meclofenamic acid reduced resting blood flow by approximately 20%.3. The increase in blood flow during 6 min periods of hypoxia was inversely related to arterial oxygen saturation and this relationship was not altered significantly by meclofenamic acid.4. The magnitude of the reactive hyperaemias following arterial occlusion for 5‐40 s was dependent on the occlusion time. The peak changes in vascular conductance relative to the resting values were similar before and after administration of meclofenamic acid.5. Direct stimulation of the muscles of the hind limb with 0.5‐5 Hz produced frequency‐dependent increases in blood flow and oxygen uptake to the limb. Although these responses were depressed after meclofenamic acid, the relationship between blood flow and oxygen uptake was not changed. The responses to stimulation with 10 Hz were not affected by meclofenamic acid.6. An isolated chick rectum, superfused with re‐oxygenated venous blood from the hind limb during muscle stimulation at 10 Hz showed an initial relaxation, followed by contraction. The contraction was abolished after administration of meclofenamic acid.7. From these results it appears that the release of prostaglandins is not essential for hyperaemais associated with vessel occlusion, systemic hypoxia or muscle exercise.