The kinetics of extracellular potassium changes during hypoxia and anoxia in the cat cerebral cortex.
Extracellular potassium activity, [K+]0, was continuously measured using potassium specific microelectrodes in the cerebral cortex of cats before and after hypoxic or anoxic insults. Two patterns of [K+]0 increase were seen. A slow, linear rise occurred during hypoxia and hypothermia and was correlated with changes in mean blood pressure (B/P). A fast, complex, exponential rise resembling spreading depression occurred during anoxia and was unassociated with B/P changes. The fall of [K+]0 after reversal of the insult was described by a single exponential function with rate constants from 0.009 to 0.0194 sec-1. It is suggested that the linear rise is primarily a result of sodium pump inhibition and that the exponential rise is due to a superimposed sudden increase in cell membrane permeability perhaps secondary to transmitter release. The kinetics of the fall of [K+[0 is consistent with the normalization of the sodium and potassium gradients across the cell membranes secondary to Na+-K+ATPase activity.
D000818:Animals; D001692:Biological Transport; D001794:Blood Pressure; D001921:Brain / Q000503:physiopathology; D002415:Cats; D002540:Cerebral Cortex / Q000378:metabolism*; D002698:Chloralose / Q000494:pharmacology; D004594:Electrophysiology; D002534:Hypoxia, Brain / Q000378:metabolism* / Q000503:physiopathology; D007700:Kinetics; D010634:Phenobarbital / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*
D002698:Chloralose; D011188:Potassium; D010634:Phenobarbital