Spasmogenic action of endothelin-1 on isolated equine pulmonary artery and bronchus.

Summary

# Editorial Summary: Endothelin-1 and Equine Airway Responses Endothelin-1 (ET-1) is a potent endogenous vasoconstrictor produced within the body, yet its specific effects on equine pulmonary vessels and airways—and which receptor subtypes mediate these responses—remained poorly characterised prior to this investigation. Benamou and colleagues examined isolated equine pulmonary artery and bronchial tissue preparations to determine how ET-1 induces constriction and which endothelin receptor subtypes (ETA and ETB) were responsible. ET-1 produced dose-dependent constriction of both tissues, with the pulmonary artery demonstrating particularly pronounced responses; selective ETA receptor antagonism substantially reduced vasoconstriction, whilst ETB involvement appeared secondary, though both receptor types contributed to bronchial constriction. These findings suggest that ET-1-mediated pulmonary vasoconstriction in horses is primarily ETA-dependent, which has implications for understanding equine respiratory conditions—particularly exercise-induced pulmonary haemorrhage and recurrent airway obstruction—where excessive ET-1 activity may play a pathophysiological role. Selective ETA receptor antagonists might represent a novel therapeutic avenue for managing horses with pulmonary vascular dysfunction or reactive airway disease, though further in vivo investigation would be necessary before clinical application.

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Key Findings

• •Endothelin-1 is a potent endogenous spasmogen affecting both equine pulmonary vascular and airway smooth muscle
• •Study identified which ET receptor subtypes mediate ET-1-induced vasoconstrictive and broncoconstrictive responses in horses

Conditions Studied