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 A(1) receptor antagonists, respectively, into the AVPO would exacerbate the ventilatory response and lessen the drop in body temperature (T(b)) caused by
hypoxia. We measured ventilation (V ) and T(b) of conscious Wistar rats before and after AVPO injection of
aminophylline (1 and 10 microg/100 nL) or
DPCPX (17.5 and 175 ng/100 nL), or their respective vehicles, followed by 30 min of
hypoxia (7% O(2)). Vehicles and the lower doses of both antagonists had no effect on V and T(b) during normoxia or
hypoxia. The higher doses of
aminophylline and
DPCPX increased (P<0.05) the
hypoxia-induced
hyperventilation, whereas the drop in T(b) elicited by
hypoxia was attenuated (P<00.05) by
DPCPX only. This higher
DPCPX dose also increased T(b) 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 A(1) receptors stimulation in the AVPO inhibits ventilatory drive during
hypoxia and tonically modulates basal T(b).