Abstract
Using an in vitro bioassay technique, we examined the vasoactivity of endothelin-1 (ET), a new potent vasoconstrictor peptide released from endothelial cells, in nasal mucosa obtained from the canine septum and the human inferior turbinate. Cumulative addition of ET induced contractions in a concentration-dependent manner starting at a very low concentration. ET caused slow-onset and long-lasting contractions which were difficult to reverse even when the tissue was washed repeatedly. This contraction was not blocked by any of the known receptor antagonists tested, but was completely inhibited by pretreatment with the calcium channel blocker nifedipine. Removal of extracellular calcium ions abolished ET-induced contractions. ET enhanced exogenous noradrenaline (NA)-induced contractions, but did not affect endogenous NA-induced contractions produced by electric stimuli. It is postulated that since endotheliumderived substances, such as ET, show powerful vasoreactivity, endothelial cells may play an important role in the regulation of the vasomotor tone of nasal blood vessels, along with the autonomic neural mechanism.
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