Effects of anti-asthmatic drugs on airway resistance and plasma level of cyclic AMP in guinea pig.

Iwayama, Yumiko; Chung, Chang Zer; Takayanagi, Issei

doi:10.1254/jjp.32.329

Cited by 4 publications

(1 citation statement)

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“…It is possible that the inhibitory factor, in addition to modulating directly the bronchoconstrictor effects of leukotrienes and histamine, also may decrease the release of these mediators from mast cells. Although ovalbumin-sensitization has been shown to produce increased responsiveness to histamine in guinea-pigs in vivo (Iwayama et al, 1982), it does not produce airway hyperreactivity in vitro; in fact, a decreased responsiveness to histamine and methacholine has been reported in trachea from ovalbuminsensitized guinea-pigs (Cheng & Townley, 1983;. In the present study, both the sensitivity and the maximum contractile response to LTC4, LTD4, LTE4, 5-HT and U-44069 were the same in preparations (intact and rubbed) from control and ovalbumin-sensitized guinea-pigs.…”

Section: Discussionmentioning

confidence: 99%

Differential effects of epithelium removal on the responsiveness of guinea‐pig tracheal smooth muscle to bronchoconstrictors

Hay¹,

Farmer

Raeburn

et al. 1987

British J Pharmacology

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The influence of the epithelium on contractions produced by the peptidoleukotrienes, 5‐hydroxytryptamine (5‐HT) and the thromboxane mimetic, U‐44069, was examined in trachea from control and ovalbumin‐sensitized guinea‐pigs. In control tissues removal of the epithelium produced an approximately 2 to 4 fold leftward shift in leukotriene C4 (LTC4) and LTD4 concentration‐response curves, but no effect on LTE4‐induced contractions. Similar results were obtained in preparations from ovalbumin‐sensitized animals. Responses produced by 5‐HT or U‐44069 were similar in the presence and absence of the epithelium in control guinea‐pigs. Indomethacin produced contrasting effects on leukotriene‐induced contractions in control guinea‐pigs: an increase in sensitivity to LTC4 in the presence but not absence of the epithelium, no effect on LTD4‐induced contractions and a decrease in sensitivity to LTE4 in both epithelium‐containing and epithelium‐free preparations. These results indicate that there is selectivity in the effects of epithelium removal on agonist‐induced contractions of the guinea‐pig trachea. This provides further evidence for the modulatory influence of the epithelium on the reactivity of mammalian airway smooth muscle and supports the postulated existence of an epithelium‐derived inhibitory factor. The observation that in intact trachea indomethacin mimics the effects of epithelium removal on LTC4‐induced responses, suggests the involvement of a prostanoid(s) in this phenomenon.

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Section: Discussionmentioning

confidence: 99%