[The participation of humoral factors released by the endothelium in the development of reactive hyperemia].

In anesthetized dogs and on test-preparations of isolated vascular rings of femoral artery used for detection of appearance of vasoactive substances in venous blood, the reactive hyperemia was accompanied by the appearance of vasodilation substances in blood, the concentration of which increased with the occlusion duration. Chemical injury of endothelium by saponin, inhibition of lipoxygenase by quercetin and guanylate cyclase by methylene blue decreased the reactive hyperemia and the relaxation of test-preparation. Cyclooxygenase inhibition by indomethacin did not affect the reactive hyperemia or release of vasoactive substances. The endothelium seems to play an important role in development of reactive hyperemia induced by endothelium-derived relaxing factor release.