Increased glucose availability does not restore prolonged spreading depression durations in hypotensive rats without brain injury.

Overview

Maintenance of transmembrane ionic gradients and their restoration after cortical spreading depression (CSD) are energy dependent. We recently showed an inverse relationship between blood pressure and CSD duration that is independent of tissue oxygenation. Here, we tested the alternative hypothesis that glucose availability becomes rate-limiting for CSD recovery upon reduced blood pressure in anesthetized rats under full systemic physiological monitoring. Hypotension induced by controlled exsanguination significantly prolonged CSD durations, reduced propagation speeds, and diminished the blood flow response. Hyperglycemia failed to restore the prolonged CSD durations in hypotensive rats and did not significantly alter the propagation speed or the blood flow response. These data suggest that prolonged CSD durations during reduced cerebral perfusion pressure are independent of tissue energy status, and implicate alternative mechanisms of CSD recovery such as vascular clearance of extracellular K(+).