SummaryThe aim of this study was to determine the effect of histamine and serotonin, as well as the influence of their inhibitors, on bronchoconstriction using equine precision-cut lung slices (PCLS), which were prepared from 5 horses affected by various degrees of small airway disease (SAD) and a sixth horse free of respiratory disease. Over all horses, histamine caused a concentration-dependent bronchoconstriction, with a median effective concentration of 1820 nM. The histamine induced bronchoconstriction could be inhibited by incubation with the H1-receptor antagonist cetirizine before the addition of histamine. However, incubation with the H2-receptor-antagonist ranitidine, the H2 and H3-receptor antagonist thioperamid and the H4-receptor antagonist JNJ7777120 had no significant effect. Serotonin induced a concentration-dependent bronchoconstriction in the horse without evidence of airway disease only. The serotonin-induced reaction in this case was inhibited when the PCLS was previously incubated in ketanserin. The possibility that respiratory disease could have a negative effect on the serotonin-receptor or the serotonin-induced bronchoconstriction pathway is discussed.Keywords: Bronchoconstriction / histamine / serotonin / PCLS / horse / pulmology / chronic airway disease Untersuchung der durch Histamin oder Serotonin induzierten Bronchokonstriktion in "Precision Cut Lung Slices" des Pferdes Das Ziel der Studie lag in der Untersuchung des Effektes von Histamin und Serotonin sowie des Einflusses ihrer Inhibitoren auf die