AI Article Synopsis
- The Kir2.1 channel primarily allows inward currents and shows minimal outward currents when depolarized, but barium can alter this behavior.
- In this study, barium not only blocked inward currents but also increased outward currents by about 43% after 200 seconds of exposure, despite higher concentrations managing to reduce the outward currents again.
- The effects of barium suggest a specific interaction with Kir2.1, as other substances like calcium and Chloroethylclonidine did not provide similar results; this change in current could affect cardiac action potentials and potentially shorten the QT interval in ECG readings.
Article Abstract
Kir2.1 channel is a typical inward rectified channel with little outward currents when the membrane depolarized. Barium blocks the inward Kir2.1 currents in a voltage-dependent manner. However, in this study we found that barium would impair the rectification and open Kir2.1 outward currents at a depolarized voltage, causing increment of outward current amplitudes by 43±7% (n=5, P<0.01) after 200s barium application. In the meanwhile, a higher barium concentration did block the outward currents by 17.5±4.3% (n=4, P<0.01) and temporarily twisted current upward tendency. The increment was likely barium specific since both calcium and Kir2.1 specific blocker, Chloroethylclonidine (CEC), did not enhance the current amplitudes. The rectification of Kir2.1 was not recovered by washing barium off, which suggested a non-competitive mechanism. Since the currents occurred at phase 1, 2 of cardiac action potential, it would likely shorten the action potential plateau and it would decrease QT duration in electrocardiography (ECG).
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| http://dx.doi.org/10.1016/j.ejphar.2014.02.025 | DOI Listing |
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