Non-specific Hyperreactivity to Pharmacological Stimuli in Tracheal and Lung Parenchymal Strips of Actively Sensitized Guinea-pigs

Abstract

The responsiveness of tracheal and lung parenchymal strips isolated from actively sensitized guinea-pigs to CaCl2 (in K+-depolarized tissue), KCl, acetylcholine and histamine was compared with that of strips from unsensitized animals. The concentration-response curves to the mentioned agonists exhibited, in the sensitized group, a left upward displacement (greater maximal effect, lesser effective concentration 50% and a steeper slope) compared with those obtained in the unsensitized group. These results indicate the existence of a non-specific increase in responsiveness in the airway smooth muscle from sensitized animals.

Relationship between Nonspecific Airway Hyperreactivity and Antigen-Induced Contraction in an Allergic Animal Model in vitro

“…This is in accordance with previous reports from this laboratory [20,22,25]. In addition, a signifi cant correlation was found between the magnitude of the response to BSA (1 mg/ml) and the responsive ness (Emax) and sensitivity (pD2 value) to the men tioned agonists in the sensitized tracheal strips.…”

The Role of the Mucosa in the in vitro Changes in Guinea Pig Bladder Function Which Occur after Sensitization with Ovalbumin

“…Maximal contractile re sponses and/or sensitivity to norepinephrine, histamine, BaCl, and KC1 are increased in vas deferens, ileum, trachea, and aortic prepara tions from sensitized guinea pigs [29][30][31][32], In addition, in aorta and trachea, removal of the epithelium or endothelium increases the sen sitivity to contractile agents [32,33]. How ever, it should be noted that nitric oxide release causing relaxation has been described for these tissues, and removal of the epithe lium or endothelium probably reduces the relaxant component of the response [34], Ni tric oxide-induced relaxation has not been found in the bladder body [35],…”

Strain-Related Differences in the Tracheal Responsiveness of Sensitized Guinea Pig

“…Nevertheless, such a typical nonspecific hyperreactivity has been observed in many oth er studies [25][26][27][28]. These discrepancies may be related ei ther to different animal species and/or strains used, large variation in sensitization procedures and/or tissue prepara tion and use of isotonic or isometric transducer [5], It is dif ficult to discuss whether the controversial data presented in the literature could be attributed to the use of different strains as they are not always given precisely.…”

“…The sensitization of labora tory animals, especially the guinea pig, is widely used as animal model of allergic asthma [4], Conflicting results on the in vitro hyperreactivity of the sensitized trachea may be related to different experimental procedures (animal strain, sensitization procedure) [5]. An intra-and inter-species var iability in airway responsiveness has already been noted in the guinea pig, rat, rabbit and dog [6,7], The quantity of airway smooth muscle has been demonstrated to be an im portant determinant of inter-strain differences in the rat [6, 8], Furthermore, the contractile response of the smooth muscle seems to be different after an antigen sensitization in accordance with species or strain [9,10], Very few studies have been carried out to compare the effect o f sensitization in different strains of rat [7] and guinea pig [I IJ.…”