Glibenclamide enhances cortical spreading depression-associated hyperemia in the rat

We investigated the contribution of ATP-sensitive potassium channels (K(ATP)) and calcium-activated potassium channels (Kca2+) to cortical spreading depression (CSD)-associated hyperemia using the rat closed cranial window model. The peak CBF response was enhanced by 12 +/- 5, 13 +/- 4, and 28 +/- 8% (p<0.01) of the control with 10(-6), 10(-5) and 10(-4) mol/l glibenclamide (glyb), a K(ATP) antagonist, respectively. We also calculated the area under the CBF curve to fully represent the extent of hyperemia during CSD. The area increased by 30 +/- 8 (p<0.05), 72 +/- 31 (p<0.05) and 88 +/- 20% (p<0.05) of the control with 10(-6), 10(-5) and 10(-4) mol/l glyb, respectively. However, charybdotoxin (CTX), a Kca2+ antagonist showed no effect. The effect of glyb was inhibited by pretreatment with 5 mg/kg indomethacin. We conclude that activation of K(ATP), perhaps associated with neurons, plays an inhibitory role in the CSD-associated hyperemia via an indomethacin-sensitive mechanism.