Pharmacologic characterization of wool dust extract in isolated guinea pig trachea

Airway mechanics and methods used to visualize smooth muscle dynamics in vitro

Contraction of airway smooth muscle (ASM) is regulated by the physiological, structural and mechanical environment in the lung. We review two in vitro techniques, lung slices and airway segment preparations, that enable in situ ASM contraction and airway narrowing to be visualized. Lung slices and airway segment approaches bridge a gap between cell culture and isolated ASM, and whole animal studies. Imaging techniques enable key upstream events involved in airway narrowing, such as ASM cell signalling and structural and mechanical events impinging on ASM, to be investigated.

Pharmacologic characterization of latex extracts by isolated guinea pig tracheal tissue

Latex manufacturing workers are exposed to a heterogeneous aerosol of organic compounds. Previous studies of latex workers involved in glove production indicate that these individuals are at risk of developing respiratory symptoms and impaired lung function. The effect of latex extracts on isolated guinea pig tracheal smooth muscles was studied using latex water-soluble extracts obtained at different stages of the industrial process. Latex extracts were prepared as a 1:10 (w/v) solution. Dose-related contractions of nonsensitized guinea pig trachea were demonstrated using two latex extracts (latex 1 and latex 2). Latex 1 was prepared from the native latex and latex 2 from a processed form of latex which was relatively free of soluble proteins. Pharmacologic studies were performed by pretreating guinea pig tracheal tissue with drugs known to modulate smooth muscle contraction: atropine, indomethacin, pyrilamine, nordihydroguaiacetic acid, acivicin, trimethobenzoic acid and capsaicin. Constrictor effects of the dust extracts were inhibited by a wide variety of these agents. Atropine consistently and strikingly reduced the contractile effects of these extracts. This observation may suggest an interaction of the extracts with parasympathetic nerves or more directly with muscarinic receptors. Inhibition of contraction by blocking other mediators was less effective and varied with the dust extract. Pretreatment with capsaicin did not change the constrictor effects of latex 1 but enhanced the effects of latex 2. Depletion of neuropeptides, however, did not reduce the constrictor effect. We suggest that latex extracts cause dose-related airway smooth muscle constriction by nonimmunological mechanisms involving a variety of airway mediators and possibly cholinergic receptors. This effect is not dependent on the presensitization of guinea pigs.