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Tonic adenosine neuromodulation is preserved in motor nerve endings of aged rats |
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| Authors: | Pereira M F Cunha R A Ribeiro J A |
| Affiliation: | a Laboratory of Neurosciences, Faculty of Medicine, University of Lisbon, Av. Prof. Egas Moniz, Lisbon 1649-028, Portugal b Department of Chemistry and Biochemistry, Faculty of Sciences, University of Lisbon, Campo Grande, Lisbon 1749-016, Portugal |
| Abstract: | Neuromuscular transmission is decreased in aged subject. Since endogenous adenosine is a potent neuromodulator at motor nerve endings, either inhibiting via A1 receptors or facilitating via A2A receptors acetylcholine release, we now investigated if the tonic effect of endogenous adenosine was modified at phrenic nerve endings of aged rats. The A2A receptor antagonist (ZM241385, 50 nM) inhibited (77 ± 9%) and the A1 receptor antagonist (DPCPX, 50 nM) facilitated (74 ± 13%) acetylcholine release from young adult (6 weeks old) rat preparations, indicating a simultaneous tonic activation of A2A and A1 receptors. Tonic modulation by adenosine was unaltered in aged (24 months old) rats, since ZM241385 (50 nM) inhibited (73 ± 8%) and DPCPX (50 nM) facilitated (91 ± 20%) acetylcholine release in aged animals similarly to young rats. This indicates that, in contrast to the central nervous system where adenosine neuromodulation is modified in aged animals, the control by adenosine of phrenic nerve function is preserved in aged animals |
| Keywords: | Adenosine Neuromuscular junction Phrenic nerve Motor terminals Aging A1 receptors A2A receptors Neuromodulation |
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