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Opioid μ ‐receptors in the rostral medullary raphe modulate hypoxia‐induced hyperpnea in unanesthetized rats
Author(s) -
Dias M. B.,
Nucci T. B.,
Branco L. G. S.,
Gargaglioni L. H.
Publication year - 2012
Publication title -
acta physiologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.591
H-Index - 116
eISSN - 1748-1716
pISSN - 1748-1708
DOI - 10.1111/j.1748-1716.2011.02345.x
Subject(s) - hyperpnea , hypoxia (environmental) , endocrinology , raphe , opioid , medicine , hyperventilation , raphe nuclei , chemistry , receptor , control of respiration , anesthesia , respiratory system , serotonin , serotonergic , organic chemistry , oxygen
Aim: It has been suggested that the medullary raphe (MR) plays a key role in the physiological responses to hypoxia. As opioid μ ‐receptors have been found in the MR, we studied the putative role of opioid μ ‐receptors in the rostral MR (rMR) region on ventilation in normal and 7% hypoxic conditions.Methods: We measured pulmonary ventilation () and the body temperatures (Tb) of male Wistar rats before and after the selective opioid μ ‐receptor antagonist CTAP ( d ‐Phe‐Cys‐Tyr‐ d ‐Trp‐Arg‐Thr‐Pen‐Thr‐NH2, cyclic, 0.1 μ g per 0.1 μ L) was microinjected into the rMR during normoxia or after 60 min of hypoxia.Results: The animals treated with intra‐rMR CTAP exhibited an attenuation of the ventilatory response to hypoxia (430 ± 86 mL kg −1 min −1 ) compared with the control group (790 ± 82 mL kg −1 min −1 ) ( P < 0.05). No differences in the Tb were observed between groups during hypoxia.Conclusion: These data suggest that opioids acting on μ ‐receptors in the rMR exert an excitatory modulation of hyperventilation induced by hypoxia.