Effect of pyrithiamine treatment on potassium ion fluxes in rat cortical slices.
The effect of thiamine deficiency on energy-requiring processes in brain tissue was studied by comparing cortical slices prepared from control and pyrithiamine-treated rats. Veratridine was used to stimulate energy metabolism by opening voltage-sensitive sodium channels resulting in enhanced Na+/K+ pumping; subsequent tetrodotoxin addition closed the sodium channels. Pyrithiamine-treated slices showed both lower basal and veratridine-stimulated respiration rates compared to control slices. K+ was released from the tissue upon addition of veratridine and was taken up again upon addition of tetrodotoxin. The movement of K+ was monitored directly with a K+-sensitive electrode as well as by measuring the rubidium diffusion potential. There was no difference between control and pyrithiamine-treated slices in K+ fluxes in response to veratridine and tetrodotoxin. The extent of reuptake of K+ upon tetrodotoxin addition was inversely related to the extracellular Ca2+ concentration and to the incubation temperature. Veratridine resulted in a marked decrease in tissue levels of ATP and creatine phosphate; these levels remained quite low upon tetrodotoxin addition. Despite the different respiration rates, control and pyrithiamine-treated slices showed the same ATP and creatine phosphate levels in response to veratridine and tetrodotoxin.
D000818:Animals; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D066298:In Vitro Techniques; D007700:Kinetics; D010101:Oxygen Consumption / Q000187:drug effects; D010725:Phosphocreatine / Q000378:metabolism; D011188:Potassium / Q000378:metabolism*; D011726:Pyridinium Compounds / Q000494:pharmacology*; D011745:Pyrithiamine / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013779:Tetrodotoxin / Q000494:pharmacology; D013832:Thiamine Deficiency / Q000378:metabolism*; D014701:Veratridine / Q000494:pharmacology
D011726:Pyridinium Compounds; D010725:Phosphocreatine; D013779:Tetrodotoxin; D011745:Pyrithiamine; D014701:Veratridine; D011188:Potassium