Llobet A, Gasull X, Palés J, Martí E, Gual A
Laboratori de Neurofisiologia, Departament de Ciències Fisiològiques I-Institut d'Investigacions Biomèdiques August Pi i Sunyer, Facultat de Medicina, Universitat de Barcelona, Spain.
Invest Ophthalmol Vis Sci. 2001 Sep;42(10):2371-9.
To study the presence of inwardly rectifying K(+) (Kir) channels in cultured bovine (BTM) and human (HTM) trabecular meshwork cells.
Cultures of BTM and HTM cells were obtained by an extracellular matrix digestion technique. Whole-cell patch-clamp recordings of BTM cells were performed with the appropriate solutions to detect K(+) currents. Also, Western blot analysis of Kir2.1 protein expression was performed on both cultured BTM and HTM cells.
A strong inwardly rectifying current at negative potentials to the equilibrium potential for K(+) (E(K+)) and highly selective for K(+) was detected in 60% of cultured BTM cells. The slope conductance of the inward rectification was more pronounced when the extracellular [K(+)] was increased and was proportional to K(+). The current was blocked by Ba(2+) and Cs(+) in a voltage- and concentration-dependent manner, with K(d) at 0 mV, of 74.7 microM and 45.6 mM, respectively. Current amplitude was reduced by increasing extracellular [Ca(2+)]. The current was insensitive to 10 microM glibenclamide and 10 nM tertiapin. The application of 100 microM 8-Br-cAMP reduced the current by 50%. Kir2.1 channel expression was detected in confluent monolayers of BTM and HTM cells by Western blot analysis.
A population of cultured BTM cells expressed an inwardly rectifying K(+) current that illustrates the biophysical and pharmacologic characteristics of the detected Kir2.1 channel protein. Kir2.1 channels are also thought to be present in HTM cells. Kir2.1 channels could be related to TM physiology, because they are involved in contractile and cell volume regulatory responses, two mechanisms that modify TM permeability.
研究培养的牛（BTM）和人（HTM）小梁网细胞中内向整流钾（Kir）通道的存在情况。
通过细胞外基质消化技术获得BTM和HTM细胞培养物。用适当的溶液对BTM细胞进行全细胞膜片钳记录以检测钾电流。此外，对培养的BTM和HTM细胞均进行Kir2.1蛋白表达的蛋白质印迹分析。
在60%的培养BTM细胞中检测到在负电位至钾平衡电位（E(K+)）时存在强烈的内向整流电流，且对钾具有高度选择性。当细胞外[K+]增加时，内向整流的斜率电导更明显，且与K+成比例。该电流被Ba(2+)和Cs(+)以电压和浓度依赖性方式阻断，在0 mV时的K(d)分别为74.7 microM和45.6 mM。增加细胞外[Ca(2+)]会使电流幅度降低。该电流对10 microM格列本脲和10 nM特律平不敏感。应用100 microM 8 - Br - cAMP可使电流降低50%。通过蛋白质印迹分析在BTM和HTM细胞的汇合单层中检测到Kir2.1通道表达。
一群培养的BTM细胞表达了内向整流钾电流，该电流体现了所检测到的Kir2.1通道蛋白的生物物理和药理特性。也认为HTM细胞中存在Kir2.1通道。Kir2.1通道可能与小梁网生理学有关，因为它们参与收缩和细胞体积调节反应，这两种机制可改变小梁网通透性。
