AI Article Synopsis

  • Adenosine can cause bronchospasms in asthma and COPD patients, and the study focused on how A(2B) receptors affect smooth muscle tone, ciliary movement, and mucus transport in rats and mice.
  • NECA, a broad-spectrum adenosine receptor agonist, initially caused muscle contractions but led to relaxation with repeated doses, highlighting the role of A(2B) receptors, as their inhibition blocked this relaxation.
  • A(2B) agonists like BAY 60-6583 improved mucociliary clearance and increased ciliary beat frequency, suggesting that targeting A(2B) receptors could offer new therapeutic options for respiratory conditions.

Article Abstract

Objectives: Adenosine is known to induce a bronchospasm in asthma- and COPD patients. The role of A(2B) receptors was investigated with respect to several parameters of the respiratory tract: tonus of smooth muscle, ciliary beat frequency as measured by high-speed video camera connected to a microscope (both in rats) and mucociliary clearance (MCC; transport of a fluorescent dye using a microdialysis procedure) in mice.

Key Findings:  NECA (5'-N-ethylcarboxamidoadenosine) (a non-selective adenosine receptor agonist) was able to acutely induce a contraction, which was reversed to a relaxation after repeated dosing. This relaxation was completely abolished by PSB-1115, an A(2B) receptor antagonist. IL-13 (cytokine) was not involved mediating acute contractility effects. MCC was increased by BAY 60-6583 (A(2B) receptor agonist) and NECA (counteracted by the A(2B) receptor antagonist PSB-1115). Activation of A(2B) adenosine receptors by BAY 60-6583 induced an increase of the ciliary beat frequency, which could be reduced by administration of PSB-1115. Several cytokines were increased by NECA although only some are relevant because they are not blocked by A(2B) receptor antagonism.

Conclusions: The A(2B) receptors are involved in airway relaxation, MCC improvement and ciliary beat frequency. A(2B) receptor agonists may be of therapeutic value and should be developed.

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Source
http://dx.doi.org/10.1111/j.2042-7158.2012.01580.xDOI Listing

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