Abstract: The present study was undertaken to investigate the linkage between angiotensin-(1-7) [Ang-(1-7)] and the release of amino acid neurotransmitters in the the rostral ventrolateral medulla (RVLM) by techniques of microinjection, microdialysis combined with high performance liquid chromatography (HPLC)-fluorescent detection. Unilateral microinjection of Ang-(1-7) into the RVLM of anesthetized rats produced an increase in mean arterial pressure (MAP) accompanied by an increased release of glutamate (Glu). In contrast, microinjection of Ang779, a selective antagonist of Ang-(1-7) receptor, caused a decrease in MAP with a decreased releaceof Glu and an increased release of glycine,taurine and r-aminobutyric acid.The pressor effect of Ang-(1-7)and the depressor effect of Ang779 were in part blocked by corresponding andtagonists of aminoacid receptors.These results suggest that the pressor effect of Ang-(1-7)in the RVLM may be partially due to an increased release of Glu,whereas the depressor effect of Ang779 may be partially attributed to a decreased release of Glu and an increased release of inhibitory amino acid neurotransmitters