Respiratory and body temperature modulation by adenosine A1 receptors in the anteroventral preoptic region during normoxia and hypoxia

The present study was undertaken to investigate adenosine as a simultaneous mediator of hypoxia-induced hyperventilation and regulated hypothermia in the anteroventral preoptic region (AVPO), the thermointegrative region of the central nervous system (CNS). Accordingly, we predicted that injection of aminophylline and DPCPX, non-selective and A1 receptor antagonists, respectively, into the AVPO would exacerbate the ventilatory response and lessen the drop in body temperature (Tb) caused by hypoxia. We measured ventilation (V˙) and Tb of conscious Wistar rats before and after AVPO injection of aminophylline (1 and 10 μg/100 nL) or DPCPX (17.5 and 175 ng/100 nL), or their respective vehicles, followed by 30 min of hypoxia (7% O2). Vehicles and the lower doses of both antagonists had no effect on V˙ and Tb during normoxia or hypoxia. The higher doses of aminophylline and DPCPX increased (P < 0.05) the hypoxia-induced hyperventilation, whereas the drop in Tb elicited by hypoxia was attenuated (P < 00.05) by DPCPX only. This higher DPCPX dose also increased Tb during normoxia. The present data is consistent with the notion that adenosine plays an inhibitory role in respiratory and metabolic regulation, in a way that A1 receptors stimulation in the AVPO inhibits ventilatory drive during hypoxia and tonically modulates basal Tb.