ENDOTHELIN IN HUMAN NASAL-MUCOSA

Endothelin (ET), a potent vasoconstrictor and bronchoconstrictor pepti de synthesized by endothelial and epithelial cells, was examined for i ts potential functions in human inferior turbinate nasal mucosal tissu e by four techniques: (1) immunoreactive ET was localized in the mucos a by immunohistochemistry; (2) receptors for ET were identified by aut oradiography employing [I-125]ET; (3) ET-1 mRNA was localized by in si tu hybridization; and (4) the secretory functions of ET were examined by the release of mucous and serous cell products after the addition o f ET to human nasal turbinates in short-term cultures. Specific ET-1-i mmunoreactive material was found most extensively in small muscular ar teries and in serous cells in submucosal glands. ET-1 was also found t o a lower extent in the walls of venous sinusoids. [I-125]ET-1 binding sites were localized by autoradiography to submucosal glands and to v enous sinusoids and small muscular arterioles. mRNA for ET-1 was found most extensively in the venous sinusoids and to a lesser extent in sm all muscular arteries. In mucosal explant cultures, ET-1 and ET-2 stim ulated lactoferrin and mucous glycoprotein release from serous and muc ous cells, but ET-3 was inactive. The observations indicate that in th e human nasal mucosa, ET is present in the vascular endothelium and th e serous cells in submucosal glands and acts on glandular ET receptors to induce both serous and mucous cell secretion. It is also likely th at ET plays a role in the regulation of vasomotor tone.