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Interactions of a water extract of cotton bract with dog isolated airway smooth muscle.

Fedan-JS; Franczak-MS; Cahill-JF; Kosten-CJ; Morey-P; Weber-KC
J Toxicol Environ Health 1986 Jan; 17(1):57-71
The ability of cotton bract extracts (CBE) to increase isolated respiratory smooth muscle tone was investigated with regard to their direct and indirect mechanisms of action. Crude aqueous extracts were prepared from powdered (60 mesh) frost killed cotton bracts at room temperature, filtered through 0.45 micron filters, lyophilized, and reconstituted in sterile physiological saline. Dog trachealis muscle preparations were mounted in organ chambers set up to record isometric tension. Maximal contraction produced by CBE was considerably smaller than that produced by methacholine (62511), potassium-chloride (7447407), histamine (51456), and 5- hydroxytryptamine (50679) (5-HT). Antagonists to methacholine, histamine and 5-HT reduced the contractile effects of their agonists, but had no effect on responses to CBE. Only superthreshold concentrations of CBE potentiated the contractile effects of histamine and 5-HT without affecting the 50 percent effective concentration (EC5O). Electrical stimulation produced neurogenically induced contractions blocked by atropine (51558) and potentiated by CBE. Neurogenic inhibitory responses were unaffected by CBE. The authors conclude that, in contrast to other reports in the literature, the CBE effects they observed are not mediated by muscarinic, histamine H1, or 5-HT receptors and that CBE potentiation of histamine and 5-HT effects enhances their activity after release from tissues. It is further concluded that the absence of CBE potentiation of methacholine indicates that CB acts prejunctionally to facilitate acetylcholine release. The authors speculate that the various CBE effects may be mediated by the release of prostaglandins or other smooth muscle regulators. These experimental effects of CBE are believed by the authors to be related to byssinosis, a disease of cotton mill workers whose symptoms indicate increases in airway smooth muscle tone.
NIOSH-Author; Cotton-industry; In-vitro-studies; Muscle-contraction; Laboratory-animals; Physiological-response; Muscle-tension; Cotton-dust; Muscle-tissue; Muscle-physiology; Pulmonary-system-disorders
62-51-1; 7447-40-7; 51-45-6; 50-67-9; 51-55-8
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Journal of Toxicology and Environmental Health