Continuous measurement of net potassium movements in rat brain cortex suspensions. Effects of glutamate, veratridine, creatine and other substances.
Net K fluxes in in vitro suspensions of sliced rat brain cortex were studied by means of a K-sensitive electrode. When incubation was in 3 mM K, a net K efflux occurred. It could be resolved into two first-order rate constants: k1 = 0.486 min-1, and k2 = 0.0102 min-1, that originated from compartments that contained 18% and 82% of tissue K, respectively. k1 Was suppressed by tetrodotoxin (TTX), and k2 was increased 38-fold by veratridine. The latter effect was blocked by TTX, methylphenidate (1 mM), creatine (25 mM), apamin (50 nM), quinine (100 microM), verapamil (22 microM) or D-600 (38 microM). Net K loss was greatly increased by 1 mM ouabain, and enhanced by sodium azide plus iodoacetamide, but not by 0.1 M ethanol. Glutamate (5 mM) induced a considerable and rapid net uptake of K, while aspartate or N-methylaspartate increased K efflux.
D000818:Animals; D001030:Apamin / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000187:drug effects; D002540:Cerebral Cortex / Q000378:metabolism*; D003401:Creatine / Q000494:pharmacology; D066298:In Vitro Techniques; D007473:Ion Channels / Q000378:metabolism; D007700:Kinetics; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013779:Tetrodotoxin / Q000494:pharmacology; D014701:Veratridine / Q000494:pharmacology
D007473:Ion Channels; D001030:Apamin; D013779:Tetrodotoxin; D014701:Veratridine; D003401:Creatine; D011188:Potassium