Comparison of ultra-slow, voltage-dependent inactivation of the cardiac L-type Ca2+ channel with Ca2+ or Ba2+ as the charge carrier in ferret ventricular myocytes
发布时间：2025-04-30
点击次数：
- 发布时间：
- 2025-04-30
- 论文名称：
- Comparison of ultra-slow, voltage-dependent inactivation of the cardiac L-type Ca2+ channel with Ca2+ or Ba2+ as the charge carrier in ferret ventricular myocytes
- 发表刊物：
- Exp Physiol
- 摘要：
- The whole-cell patch clamp technique was used to investigate the effect of different charge carriers upon ultra-slow voltage-dependent inactivation of L-type Ca2+ channel current in ferret ventricular myocytes at 37 degrees C. Intracellular Ca2+ was buffered with 10 mM EGTA and the membrane potential held at -40 mV. With Ba2+ as the charge carrier, the L-type current decayed throughout 20 s pulses to 0 mV as a result of ultra-slow voltage-dependent inactivation. In contrast, with Ca2+ as the charge carrier, there was no such slow decay of the current as the current decayed almost completely in the first approximately 100 ms as a result of Ca(2+)-dependent inactivation. However, with Ca2+ as the charge carrier it is still possible that ultra-slow voltage-dependent inactivation occurs. A conditioning-test pulse protocol and a second protocol were used to test for the development of ultra-slow inactivation during 20 or 30 s pulses to 0 mV with Ca2+ as the charge carrier. Ultra-slow inactivation did occur and it was qualitatively similar to that with Ba2+ as the charge carrier. The onset of ultra-slow inactivation with Ca2+ as the charge carrier could be described by the sum of two exponentials with time constants of 0.3 and 6.7 s. Recovery from ultra-slow inactivation with Ca2+ as the charge carrier was also measured with a conditioning-test pulse protocol and was best described by the sum of two exponentials with time constants of 0.5 and 6.2 s. We conclude that ultra-slow inactivation of the L-type current does occur with the physiological charge carrier, Ca2+, but it is normally masked by Ca(2+)-dependent inactivation.
- 合写作者：
- McMorn SO, Harrison SM, Zang WJ, Boyett MR
- 卷号：
- 81(4)
- 页面范围：
- 565-575
- 是否译文：
- 否
- 发表时间：
- 1996-07-16