| Electrophysiologic Effect of Desflurane on the Prolongation of Action Potential Duration in Ventricular Myocytes. |
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Sun Jun Bae, Myung Hee Kim, Jee Eun Chae, Chong Hoon Kim, Kyung Tae Min, Min Jung Lee, Wyun Kon Park |
1Department of Anesthesiology and Pain Medicine, Yonsei University College of Medicine, Seoul, Korea. wkp7ark@yumc.yonsei.ac.kr
2Department of Anesthesia and Pain Research Institute, Yonsei University College of Medicine, Seoul, Korea. |
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| Abstract |
BACKGROUND
Desflurane has been reported to prolong the QTc.
Several ionic currents that contribute to the prolongation of the action potential (AP) duration were investigated using guinea pig (GP) and rat ventricular myocytes.
METHODS
The normal APs were measured in isolated GP papillary muscles at 37 degrees C. Ventricular myocytes were obtained from GP and rat hearts. Both the delayed outward K+ current (I(K)) and the inward rectifier K+ current (I(KI)) were assessed using a voltage ramp protocol. A more detailed study on the I(K) was performed. The ICa, L was measured. In the rat ventricular myocytes, the transient outward K+ current (I(to)) was obtained. All the patch clamp experiments were carried out at room temperature. The values are presented as mean +/- SD.
RESULTS
0.91 mM desflurane significantly prolonged the APD in the GP ventricular myocytes. Using a linear voltage ramp protocol, the I(KI) at -130 mV and the peak outward I(KI) at -60 to -50 mV were not found to be significantly reduced by 0.78 and 1.23 mM desflurane, respectively. However, the peak outward I(K) at +60 mV was significantly reduced to 63 +/- 19% and 58 +/- 12% of the baseline by 0.78 and 1.23 mM desflurane, respectively. At a membrane potential of +60 mV, 0.78 and 1.23 mM desflurane reduced the Ito to 80 +/- 8% and 68 +/- 7%, respectively. A concentration-dependent reduction in the ICa, L was observed.
CONCLUSIONS
The prolongation of the APD induced by clinically relevant concentrations of desflurane in GP and rat ventricular myocytes is most likely the result of I(K) and I(to) suppression. |
| Key Words:
action potential; delayed outward K+ current; desflurane; inward rectifier K+ current; transient outward K+ current; ventricular myocytes |
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