There is evidence that astrocytes modulate synaptic transmission in the NTS interacting with glutamatergic and purinergic mechanisms. Here, using in situ working heart-brainstem preparations we evaluated the involvement of astrocyte and glutamatergic/purinergic neurotransmission in the processing of autonomic and respiratory pathways in the NTS of control and rats exposed to sustained hypoxia (SH). Baseline autonomic and respiratory activities and the responses to chemoreflex activation (KCN) were evaluated before and after microinjections of fluorocitrate (FCt, an astrocyte metabolic inhibitor) and kynurenic acid and PPADS (non-selective antagonists of glutamatergic and purinergic receptors) into the rostral aspect of the caudal commissural NTS. FCt had no effects on the baseline parameters evaluated but reduced the bradycardic response to chemoreflex activation in SH rats. FCt combined with kynurenic acid and PPADS in control rats reduced the baseline duration of expiration, which was attenuated after SH. FCt produced a large increase in the PN frequency discharge in control rats, which was reduced after SH, indicating reduction in the astrocyte modulation after SH. The data shows that a) the bradycardic component of the peripheral chemoreflex is reduced in SH rats after astrocytes inhibition; b) the inhibition of astrocytes in the presence of double antagonists in the NTS affects modulation of baseline duration of expiration in control but not in SH rats, and c) the autonomic and respiratory responses to chemoreflex activation are mediated by glutamatergic and purinergic receptors in the rostral aspect of the caudal commissural NTS.