[The vasoactivity of endothelin in the nasal mucosa]

Endothelin (ET), a novel endothelium-derived vasoconstrictor peptide with 21 amino acid residues, has recently been isolated from the supernatant of cultured porcine aortic endothelial cells. Several authors reported preliminary results demonstrating that ET has a potent contractile action in vascular smooth muscles, but its effect is slightly different in each target tissue. In the present study, we have examined the vasoactivity of ET in human and canine nasal mucosa with in vitro bioassay. The results are as follows. 1) ET induced a slow, and very sustained contraction from 10(-9) M. This response is stronger than that of noradrenaline (NA) and continued for 6-12 hours. 2) Under the sustained contraction by the administration of alpha 1 adrenoceptor agonist (methoxamine), ET induced an additional contractile response. 3) The response of ET depended on the concentration of Ca2+. 4) ET did not affect the contraction of vascular smooth muscle which was caused by the electrical stimulation. 5) ET increased the contraction of vascular smooth muscle which was caused by the administration of NA into the bath solution.