Enhancement of the Responsiveness of Vas Deferens and Ileum Smooth Muscle in Sensitized Guinea Pigs: In vitro Study

Abstract

Changes in the reactivity of the ileum (to histamine and barium chloride) and vas deferens (to acetylchohne and barium chloride), isolated from actively egg albumen-sensitized guinea pigs, have been investigated. The study was performed on 2 guinea pig strains: the Dunkin-Hartley strain, usually used as an airway allergic model, and the BFA strain. In actively sensitized guinea pigs of both strains, concentration-response curves exhibited a significant dose-dependent upward shift compared to those obtained in control guinea pigs. The maximal contraction strength calculated from these curves was significantly enhanced in both sensitized guinea pig strains, without a change in EC₅₀ values. This study showed that the active antigen sensitization procedure involved several smooth muscle functions, and not exclusively the trachea.

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

“…Further investigations in the tracheal smooth muscle structure in both strains should be considered. It should be noted that the difference between the two guineapig strains was not found when using preparations isolated from other organs: hyperreactivity was similarly present in the vas deferens and ileum isolated from both strains [12], which would indicate that the strain-related difference in the sensitization-induced increase of the responsiveness would only be located in the trachea.…”

“…Active sensitization was performed by 1 subcutaneous injection/day for 5 days of 0.5 ml of egg albumen dissolved in 1 v/v bidistilled water (26 ug albumen protein/day) [12]. Animals in the control groups were treated in the same manner with saline solution.…”

Changes in resting membrane potential induced by active sensitization in the guinea-pig vas deferens

“…However, interestingly, denervation-induced supersensitivity in the guineapig vas deferens also leads to partial depolarization of the resting membrane potential (E r ) in relation with a decreased density of functional Na + -K + pump sites (Fleming and Westfall 1975;Gerthoffer et al 1979;Wong et al 1981). Thus, in the present study, by analogy with our previous findings of hyperreactivity in actively sensitized guinea-pig vas deferens (Bidon et al 1994(Bidon et al , 1995, we have investigated whether hyperresponsiveness, induced by active sensitization with ovalbumin of the guinea-pig vas deferens, was associated with depolarization and (or) hyperpolarization of E r . As we did find an alteration in E r after active sensitization, the possible involvement of the Na + -K + pump was analyzed in another series of experiments by quantifying the total concentration of [ 3 H]ouabain binding sites and by measuring 86 Rb efflux and Na + -K + contents using vas deferens from control and sensitized guinea-pigs.…”

“…Saline solution was injected in the same manner in the animals from the control group. Measurements were carried out 29-33 days after the first injection (Bidon et al 1994). During the interval after sensitization and on the day of the experiment, guinea-pigs did not exhibit any sign of discomfort and (or) sickness.…”