1. Brain Research Centre, Department of Psychiatry, University of British Columbia, British Columbia T2N 2B5, Canada
2. Department of Pharmacology & Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, USA

Correspondence to: Brian A. MacVicar¹ Correspondence and requests for materials should be addressed to B.A.M. (Email: bmacvicar@brain.ubc.ca).

Abstract

Calcium signalling in astrocytes couples changes in neural activity to alterations in cerebral blood flow by eliciting vasoconstriction or vasodilation of arterioles. However, the mechanism for how these opposite astrocyte influences provide appropriate changes in vessel tone within an environment that has dynamic metabolic requirements remains unclear. Here we show that the ability of astrocytes to induce vasodilations over vasoconstrictions relies on the metabolic state of the rat brain tissue. When oxygen availability is lowered and astrocyte calcium concentration is elevated, astrocyte glycolysis and lactate release are maximized. External lactate attenuates transporter-mediated uptake from the extracellular space of prostaglandin E₂, leading to accumulation and subsequent vasodilation. In conditions of low oxygen concentration extracellular adenosine also increases, which blocks astrocyte-mediated constriction, facilitating dilation. These data reveal the role of metabolic substrates in regulating brain blood flow and provide a mechanism for differential astrocyte control over cerebrovascular diameter during different states of brain activation.

1. Brain Research Centre, Department of Psychiatry, University of British Columbia, British Columbia T2N 2B5, Canada
2. Department of Pharmacology & Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, USA

Correspondence to: Brian A. MacVicar¹ Correspondence and requests for materials should be addressed to B.A.M. (Email: bmacvicar@brain.ubc.ca).

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