Pérez G J, Toro L, Erulkar S D, Stefani E
Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030.
Am J Obstet Gynecol. 1993 Feb;168(2):652-60. doi: 10.1016/0002-9378(93)90513-i.
The purpose of our study was to detect and characterize potassium channels in the plasma membrane of smooth muscle cells from human myometrium.
Plasma membrane vesicles were incorporated into lipid bilayers to record single potassium channel activity.
We predominantly found a "maxi" calcium-activated potassium channel (261 picosiemens). This channel was calcium (micromoles per liter range) and voltage sensitive, highly selective for K+ over Na+ and Cs+, and was sensitive to external tetraethylammonium (dissociation constant approximately 220 mumol/L) and charybdotoxin (dissociation constant approximately 23 nmol/L). External apamin and 4-aminopyridine had no effect on this channel. Another type of potassium channel that was less frequently observed was also identified. It had a smaller conductance (142 picosiemens) and it seemed to be calcium independent (up to 50 nmol/L).
Human myometrium possesses abundant "maxi" calcium-activated potassium channels. This channel shares common characteristics with other "maxi" calcium-activated potassium channels, including calcium and voltage gating, high conductance and selectivity, and channel pharmacologic profile.
我们研究的目的是检测和鉴定人子宫肌层平滑肌细胞质膜中的钾通道。
将质膜囊泡整合到脂质双层中以记录单个钾通道的活性。
我们主要发现了一种“大电导”钙激活钾通道（261皮西门子）。该通道对钙（微摩尔/升范围）和电压敏感，对K + 的选择性远高于Na + 和Cs + ，并且对外部四乙铵（解离常数约为220μmol / L）和蝎毒素（解离常数约为23 nmol / L）敏感。外部蜂毒明肽和4-氨基吡啶对该通道没有影响。还鉴定出另一种较少见的钾通道类型。它的电导较小（142皮西门子），并且似乎不依赖钙（高达50 nmol / L）。
人子宫肌层拥有丰富的“大电导”钙激活钾通道。该通道与其他“大电导”钙激活钾通道具有共同特征，包括钙和电压门控、高电导和选择性以及通道药理学特征。
