Angiotensin(1-7) (Ang1-7) has recently emerged as an important player in both peripheral and central renin-angiotensin systems. Ang(1-7) is generated by angiotensin converting enzyme-2 from angiotensin I or angiotensin II and that some of its effects are mediated by the Mas receptor (Kostenis et al. 2005). The Mas receptor in the brain including the ventrolateral medulla has been shown to be both abundant and functionally important for cardio-vascular homeostasis (Becker et al. 2007). However, the cellular mechanisms of Ang(1-7) action in the brain remain elusive. We hypothesised that glia could be involved in Ang(1-7) signalling in the ventrolateral medulla. Ca²⁺ signalling in astrocytes of ventro-lateral medulla was studied using the novel high fidelity genetically engineered Ca²⁺ sensor Case12 (Souslova et al. 2007) targeted specifically to astroglia using adenoviral vectors (ADV). The expression was controlled with a truncated version of GFAP promoter enhanced using previously described two-step transcriptional amplification strategy (Liu et al. 2006). Organotypic slices were prepared from brainstem of P7-8 rats and transduced as per (Teschemacher et al. 2005) with ADV-sGFAP-Case12. 7-10 days later slice cultures were transferred into a recording chamber, perfused with bicarbonate-buffered artificial cerebro-spinal fluid at 34°C and astroglia were imaged using a Leica confocal microscope. Ang(1-7) at 200 nM slightly but significantly increased [Ca²⁺]_i in 12/15 astrocytes by 13±1% while 2 μM resulted in an increase of 41 ± 9%. Blockers of glutamatergic transmission CNQX (10 μM) and dAP5 (50 μM) had no obvious effect on resting [Ca²⁺]_i levels. However, both the ionotropic glutamate receptor antagonists strongly potentiated the effect of Ang(1-7). Thus, 200 nM Ang(1-7) & 10 uM CNQX increased [Ca²⁺]_i by +177 ± 4% (n=13) while 200 nM Ang(1-7) & 50 μM dAP5 raised levels by +155±25% (n=15). Thus, a direct excitatory effect of Ang(1-7) on astroglia is masked by the presence of glutamate-mediated transmission perhaps via release of an inhibitory transmitter from adjacent neurones. Consistent with this idea, the sodium channel blocker – TTX (1 μM) triggered increases in [Ca²⁺]_i in ventrolateral medullary astroglia (83±17%). We suggest that Ang(1-7) possibly acts on both neurones and glia in the ventro-lateral medulla and that the direct effect of Ang(1-7) on astroglia is excitatory.