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Vitamin A deficiency promotes bronchial hyperreactivity in rats by altering muscarinic M2 receptor function
Journal article   Open access   Peer reviewed

Vitamin A deficiency promotes bronchial hyperreactivity in rats by altering muscarinic M2 receptor function

Stephen E McGowan, Jennifer Smith, Amey Jo Holmes, Lori A Smith, Thomas R Businga, Mark T Madsen, Ulla C Kopp and Joel N Kline
American journal of physiology. Lung cellular and molecular physiology, Vol.282(5 26-5), pp.1031-1039
2002
DOI: 10.1152/ajplung.00319.2001
PMID: 11943668
url
https://doi.org/10.1152/ajplung.00319.2001View
Published (Version of record) Open Access

Abstract

Vitamin A deficiency (VAD) remains an important health problem among children in developing countries. Children living in these areas have a higher mortality from respiratory infections, which likely results in part from suboptimal nutrition, including VAD. Bronchial hyperreactivity can follow viral respiratory infections and may complicate the recovery. To investigate whether VAD promotes bronchial hyperreactivity, we have assessed methacholine-induced bronchoconstriction in VAD and vitamin A-sufficient rats. Bronchial constriction developed at lower concentrations of inhaled methacholine in VAD than in vitamin A-sufficient rats. This did not result from an increase in the bronchial wall thickness or the clearance of a small molecule (with a size similar to methacholine) from the air space. The function and abundance of the muscarinic M(2) receptors in bronchial tissue were reduced in VAD rats, suggesting that this receptor may contribute to these animals' diminished ability to limit cholinergic-mediated bronchoconstriction. A similar reduction in muscarinic M(2) receptor function has been observed in asthma. Vitamin A (retinol) and its congeners (retinoids) may be required to regulate bronchial responsiveness in addition to maintaining a normal bronchial epithelium.

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