Guinea pig bronchus as a model for icosanoid studies

Strips of guinea pig bronchus dissected from the upper, middle, and lower lobe and divided in two segments referred to as external and internal bronchi, were analyzed for their reactivity to several icosanoids. The external bronchi produced much more contractile force than the internal bronchi, and the reactivity to the agonists was different. The order of potency of prostanoids and histamine on the external bronchus was U44069 congruent to histamine greater than PGF2 alpha and on the internal bronchus U44069 greater than histamine greater than PGF2 alpha. The internal bronchus did not react to PGE2, whereas this agonist produced a dose-dependent relaxation on the external bronchus. The order of potency of leukotrienes and histamine on the external bronchus was LTD4 greater than LTC4 greater than LTE4 greater than LTA4 greater than histamine and on the internal bronchus LTC4 greater than LTD4 greater than LTA4 = LTE4 greater than histamine. LTB4 has a significant myotropic activity on guinea pig bronchus. Because of its sensitivity and characteristic responses to icosanoids, it is suggested that the guinea pig bronchus may be as suitable (and possibly more) a pharmacological preparation as the trachea or the parenchyma to study the bronchoreactivity.