Multiple Muscarinic Receptor Subtypes Mediating Pulmonary Oedema in the Rabbit

✍ Scribed by A. Delaunois; P. Gustin; M. Ansay

• Publisher: Elsevier
• Year: 1994
• Tongue: English
• Weight: 420 KB
• Volume: 7
• Category: Article
• ISSN: 0952-0600
• DOI: 10.1006/pulp.1994.1022

✦ Synopsis

SUMMARY: The effects of various muscarinic antagonists on acetylcholine (ACh)-induced pulmonary oedema were studied in isolated perfused rabbit lungs. ACh induced a dose-dependent increase in the capillary filtration coefficient ((\mathbf{K}, \mathbf{c})). This effect has been previously related to the activation of the capsaicin-sensitive nerve fibres and the release of substance P. Atropine, pirenzepine ( (\mathbf{M}{4})-selective antagonist) and 4-DAMP ( (\mathbf{M}{3})-selective antagonist) altered this response, producing a dose-dependent shift to the right of the (\mathrm{ACh}) concentration-K, response curve. By contrast, the (M_{2})-selective antagonist AFDX-116 shifted the ACh concentration-response curve to the left. Atropine, pirenzepine and 4-DAMP also significantly reduced the capsaicin-induced increase in the Kf,c, while AFDX-116 enhanced it. We conclude that multiple muscarinic receptor subtypes are present in the rabbit lung, located on the C-fibres, and are involved in the ACh-induced pulmonary oedema. (\mathbf{M}{1}) and (\mathbf{M}{3}) receptors seem to stimulate the release of neuropeptides from C-fibres, whereas (\mathbf{M}_{2}) receptors have an inhibitory effect on these fibres.