Voltage-independent barium-permeable channel activated inLymnaea neurons by internal perfusion or patch excision |
| |
Authors: | Bruce Yazejian Lou Byerly |
| |
Institution: | (1) Section of Neurobiology, Department of Biological Sciences, University of Southern California, 90089-0371 Los Angeles, CA;(2) Present address: Jules Stein Eye Institute, UCLA School of Medicine, 90024-1771 Los Angeles, CA |
| |
Abstract: | Summary Isolated nerve cells fromLymnaea stagnalis were studied using the internal-perfusion and patch-clamp techniques. Patch excision frequently activated a voltage-independent Ba2+-permeable channel with a slope conductance of 27 pS at negative potentials (50mm Ba2+). This channel is not seen in patches on healthy cells and, unlike the voltage-dependent Ca channel, is not labile in isolated patches. The activity of the channel in inside-out patches is unaffected by intracellular ATP, Ca2+ below 1mm or the catalytic subunit of cAMP-dependent protein kinase but is reversibly blocked by millimolar intracellular Ca2+ or Ba2+. The channel can be activated in on-cell patches by either internal perfusion with high Ca2+ or the long-term internal perfusion of low Ca2+ solutions not containing ATP. These channels may carry the inward Ca2+ current which causes a regenerative increase in intracellular Ca+ when snail neurons are perfused with high Ca2+ solutions. High internal Ca2+, or long periods of internal perfusion with ATP-free solutions, induces an increase in a resting (–50 mV) whole-cell Ba2+ conductance. This conductance can be turned off by returning the intracellular perfusate to a low Ca2+ solution containing ATP and Mg2+. The activity of this channel appears to have an opposite dependence on intracellular conditions to that of the voltage-dependent Ca channel. |
| |
Keywords: | barium current internal perfusion patch clamp |
本文献已被 SpringerLink 等数据库收录! |
|