[Evidence for the presence of endothelium-derived relaxing factor in nasal blood vessels]

It has widely been recognized that the vascular endothelium plays an important role in the regulation of vascular tension. Endothelium-derived relaxing factor (EDRF) is a potent vasodilator produced by vascular endothelial cells in response to acetylcholine (ACh) and a variety of other substances. Recent studies have indicated its pharmacological and biochemical effect on vascular smooth muscle tension. The role of the vascular endothelium in the vasodilatory response to ACh stimulation was studied in isolated mucosa from the canine nasal fossa. (1) In the presence of intact endothelium, dose-dependent relaxation was induced by administration of ACh (10(-8)-10(-5)M) under sustained constriction by methoxamine. (2) After endothelial cell injury had been induced by administration of 15-hydroperoxyeicosa tetraenoic acid (15-HPETE), the relaxing response to ACh was abolished with the induction of contraction. (3) Pretreatment with a cyclo-oxygenase inhibitor (indomethacin) did not change the vasodilatory response to ACh stimulation. These results indicate that endothelium is necessary for relaxation in response to ACh, and suggest the presence of EDRF in vessels of the canine nasal mucosa.