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.