Thepotassium current carriedbyTREK-1channelsinrat cardiac ventricular muscle
2015
We studied the potassium current flowing through TREK-1 channels in rat cardiac ventricular myocytes. We separated the TREK-1 current from other current components by blocking most other channels with a blocker cocktail. We tried to inhibit the TREK-1 current by activating protein kinase A (PKA) with a mixture of forskolin and isobutyl- methylxanthine (IBMX). Activation of PKA blocked an out- wardly rectifying current component at membrane potentials positive to −40 mV. At 37 °C, application of forskolin plus IBMX reduced the steady-state outward current measured at positive voltages by about 52 %. Application of the potassium channel blockers quinidine or tetrahexylammonium also re- duced the steady-state outward current by about 50 %. Taken together, our results suggest that the increase in temperature from 22 to 37 °C increased the TREK-1 current by a factor of atleast5andthattheaveragedensityoftheTREK-1currentin rat cardiomyocytes at 37 °C is about 1.5 pA/pF at +30 mV. The contribution of TREK-1 to the action potential was assessed by using a dynamic patch clamp technique. After subtraction of simulated TREK-1 currents, action potential duration at 50 or 90 %r epolarisation was increased by about 12 %, indicating that TREK-1 may be functionally important in rat ventricular muscle. During sympathetic stimulation, inhibi- tion of TREK-1 channels via PKA is expected to prolong the action potential primarily in subendocardial myocytes; this may decrease the transmural dispersion of repolarisation and thus may serve to prevent the occurrence of arrhythmias.
Keywords:
- Correction
- Cite
- Save
- Machine Reading By IdeaReader
60
References
0
Citations
NaN
KQI