Бойко Н. Modulating influence of varying concentration of extracellular potassium ions on the properties of voltage-gated potassium conductivity of pheochromocytoma cells PC-12

The dissertation is devoted to research of modulatory influence of varying concentration of extracellular potassium ions on the properties of voltage-gated potassium conductivity of pheochromocytoma PC-12 cells. It was found that increase in extracellular K+ concentration accelerated the slow inactivation of potassium conductivity of pheochromocytoma cells PC-12 and decreased the sensitivity of inactivation rate to change of membrane potential. It is shown that during repetitive activation of potassium conductivity with certain period in cells PC-12 there is a phenomenon of cumulative inactivation. This inactivation is sensitive to extracellular K+ concentration changes. U-shaped dependence of slow inactivation on membrane potential has been found. Such a kind of slow inactivation is significantly different from C- and P/C- inactivation types and to some extend is dependent on extracellular K+ concentration. It was demonstrated that changes of extracellular K+ concentration influences on the effectiveness of tetraethylammonium (the potassium channels blocker). This gives the evidence of the dynamic properties of potassium channel's selective filter.