Changes of electrical activity and surface potassium concentration of the brain during ischaemia and reperfusion

Electrical activity and surface potassium ion concentration of the dog brain showed characteristic changes during acute ischaemia caused by 1-to 5-min occlusion of the aorta and during subsequent reperfusion. The present results show that (1) brain surface potassium concentration increases slowly during ischaemia, however, a sudden elevation ensues 3.07 +/- 1.03 min after the start of occlusion; (2) the higher the arterial glucose level is, the later this steep elevation of potassium concentration develops; (3) restitution of electrical activity of the brain during reperfusion, after an ischaemic period when potassium concentration was significantly elevated, occurred significantly later than during reperfusion after an ischaemic episode when the increase of surface potassium concentration was only moderate.