Taxini CL, Bícego K, Takakura A, Moreira T, Gargaglioni L (2011) Noradrenergic neurons of the A5 region play a role on hypoxic ventilatory response in unanesthetized rats. Neuroscience 2011 Abstracts 345.09. Society for Neuroscience, Washington, DC.
Summary: The ventrolateral pons contains the A5 group of noradrenergic neurons which is involved in cardiorespiratory control. These cells are strongly activated by carotid body stimulation and display central respiratory modulation. Recently, we showed that A5 neurons contribute to the cardiorespiratory effects elicited by chemoreflex stimulation in anesthetized rats. In the present study, we assessed the role of A5 noradrenergic neurons on cardiorespiratory responses produce by hypoxia in unanesthetized rats. To selectively destroy noradrenergic neurons, we administered the immunotoxin anti-dopamine β-hydroxylase-saporin (anti-DβH-SAP, 200nL) bilaterally in the A5 region of male Wistar rats (n = 8). Hypoxia (7% O2, 30 min) produced an increase in ventilation (Ve) (1470 ± 141 mLkg-1min-1), respiratory frequency (RF) (179 ± 139 brethsmin-1) and heart rate (484 ± 29 bpm), without affect mean arterial pressure (MAP) in conscious rats. Bilateral destruction of the catecholaminergic A5 neurons reduced the hypoxia-induced hyperventilation (942 ± 110 mLkg-1min-1, p<0.05), increase in RF (139 ± 11 breathsmin-1, p<0.05) and tachycardia (399 ± 39 bpm, p<0.05). These results suggest that A5 noradrenergic neurons contribute to the increase in heart rate, ventilation and respiratory frequency during peripheral chemoreflex stimulation.
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