Brain activity is tightly correlated with blood flow changes, a process defined as neurovascular coupling (NVC). An understanding of the signaling events underlying NVC is crucial given the vast number of cerebrovascular-associated disorders showing compromised functional hyperemia in the brain. We hypothesize that hemodynamic changes are rapidly sensed by perivascular astrocytes and tranduced to neighboring neurons adjusting, in this way, activity to blood flow supply. Disruption to this delicate form of communication is a major contributor of cerebrovascular-associated disorders such as hypertension. We thus evaluated if hemodynamic changes within parenchymal arterioles altered glial and/or neuronal activity in cortical brain slices from rats. We used a novel in vitro approach, which incorporates flow/pressure into cannulated parenchymal arterioles, while simultaneously measuring Ca2+ activity (confocal imaging) in perivascular astrocytes and firing activity (patch-clamp electrophysiology) from cortical pyramidal neurons. Values represent means ± SEM; comparisons include paired t-test and unpaired t-test for comparisons between WKY vs. SHR. At a steady flow rate (0.5 μl/min), parenchymal arterioles developed myogenic tone (17±4% constriction). In healthy rats, increased arteriolar flow rate altered Ca2+ oscillation frequency in cortical astrocytes. Responses revealed the presence of two types of astrocyte Ca2+ patterns: excitatory responses (54%) with a corresponding increase in Ca2+ oscillation frequency from 0.026±0.003 to 0.044±0.0003 Hz, P<0.0001 and inhibitory responses (46%) with a decrease in Ca2+ oscillation frequency from 0.05±0.003 to 0.03±0.0003 Hz, P<0.0001. Moreover, increased flow/pressure was associated with a reduction in pyramidal neuron firing rate (0.33±0.10 to 0.05±0.03 Hz, P<0.01) and membrane hyperpolarization (-41.50±3.13 to -44.10±2.97, P<0.005). In the presence of the gliotoxin L-aminoadipic acid, no changes in flow-induced neuronal hyperpolarization were observed (P=0.31) suggesting the participation of astrocytes in vascular-to-neuronal signaling. Next, we compared vascular reactivity in parenchymal arterioles from normotensive (WKY) vs. hypertensive (SHR) rats. Bath applied U46619 (150 nM), a thromboxane agonist, significantly increased vascular tone in SHR vs. WKY (42.06% vs. 29.78%; P<0.05). To determine if higher levels of tone compromised NVC mechanisms, arterioles were exposed to 10 mM K+, a potent vasodilatory signal involved in NVC. Responses from SHR were significantly higher when compared to WKY (26.63% vs. 12.43%; P<0.05). The present study supports reverse flow of communication at the neurovascular unit and suggests that hemodynamic changes are encoded into distinct astrocyte/neuronal responses. Moreover, we show that vascular tone is increased in SHR rats with no apparent changes in K+ signaling.