Modulating Effects of Core Oligoadenylate on the Voltage-Operated Potassium Channels in Rat Pheochromocytoma Cells |
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Authors: | Kucher V V Rozhmanova O M Pogorelaya N Kh Dolgaya E V Magura I S |
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Institution: | (1) National Academy of Sciences of Ukraine, Bogomolets Institute of Physiology, Kyiv, Ukraine |
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Abstract: | We studied modulating influences of a core oligoadenylate, 2,5-ApApA, on the voltage-operated potassium channels; the agent was injected into cloned cells of the rat pheochromocytoma PC-12. Diffusion of 2,5-ApApA from a micropipette into the cell evoked clear changes in the current-voltage relationships of the integral potassium current; when positive shifts of the membrane potential reached about +20 mV, a saturation phenomenon was observed. The dependence of the probability for open state of the voltage-operated potassium channels on the membrane potential was calculated using normalization of the potassium conductance graphs; it satisfactorily fit Boltzmann's equation. Under the influence of 2,5-ApApA, activation of the potassium channels became more strongly dependent on the voltage. Within the first minutes of the action of core oligoadenylate, the potassium conductance changed by e times at a shift of the membrane potential by 12 mV, while after a stationary level of the 2,5-ApApA effect had been attained (approximately from the 25th min), the same change in the potassium conductance needed only an 8-mV shift. We conclude that 2,5-ApApA-evoked conformation modifications in the structure of the potassium channels in the cells of rat PC-12 pheochromocytoma can result from an increase in the sensitivity of voltage sensors in the above-mentioned channels to changes in the membrane potential. |
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Keywords: | 2" target="_blank">gif" alt="prime" align="BASELINE" BORDER="0"> 5-oligoadenylates" target="_blank">gif" alt="prime" align="BASELINE" BORDER="0">-oligoadenylates voltage-operated potassium channels pheochromocytoma PC-12 |
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