PMID: 9185978Jun 1, 1997Paper

Muscarinic hyperresponsiveness of antigen-sensitized feline airway smooth muscle in vitro

American Journal of Veterinary Research
R W MitchellP Padrid

Abstract

To determine the effect of in vivo antigen sensitization (Ascaris suum) of cats on tracheal smooth muscle (TSM) and bronchial smooth muscle (BSM) muscarinic reactivity in vitro. Healthy domestic shorthair cats of either sex. Cats were sensitized and were long-term antigen (or sham) challenge exposed for 6 weeks by aerosolization with soluble Ascaris suum. Tracheal and BSM preparations were obtained and stimulated in vitro by electrical field stimulation (EFS), acetylcholine (ACh, a muscarinic agonist), and physostigmine (an AChase inhibitor). Responses were compared with responses of comparable tissues from sham antigen challenge-exposed cats. Tracheal and BSM from sensitized, compared with sham-sensitized (control), cats had greater isometric contraction (expressed as percentage of the response observed for isotonic, 63 mM KCl-elicited contraction [% KCl]) in response to endogenous (EFS) and exogenous muscarinic receptor activation (ACh). Contractions in response to EFS by TSM from control cats were 74% KCl vs 97% KCl for antigen-sensitized TSM (P < 0.04). Muscarinic responses were augmented comparably by in vivo sensitization; TSM from control cats contracted to 190% KCl vs 230% KCl (P < 0.03) for TSM from immune-sensitized c...Continue Reading

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