Chanson M, Roy C, Spray D C
Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461.
Am J Physiol. 1994 Feb;266(2 Pt 1):C569-77. doi: 10.1152/ajpcell.1994.266.2.C569.
Properties of gap junction channels present between specific cell types constituting the hepatopancreas of the crayfish (Procambarus clarkii) were investigated using the dual whole cell voltage clamp technique. Four different cell types (E, Fe, R and B) were identified on the basis of their morphology using light and electron microscopy. Although junctional conductance (Gj) could not be measured in B-B cell pairs, junctional currents were resolved in both homologous and heterologous combinations of the other cell types. E-E, Fe-Fe, and E-Fe cell pairs exhibited strong dependence on inside-out voltage (Vi-o), such that Gj increased with hyperpolarization to a maximal plateau reached at approximately -40 mV and was abolished with depolarization > 10 mV. The Gj-Vi-o relationship can be described by a squared Boltzmann relation with A = 0.101 and V0 = 0.135 mV. In this system, sensitivity of the junctions to transjunctional voltage was slight, if present at all. Gating mechanisms were complex, as evidence by the presence of multiple unitary channel conductance states. Single channel recordings showed that large unitary conductances (> 200 pS) were generally found between E-E, Fe-Fe, and E-Fe cell pairs, whereas smaller channel sizes (< 90 pS) were detected between R-R cell pairs.
利用双全细胞膜片钳技术研究了构成小龙虾（克氏原螯虾）肝胰腺的特定细胞类型之间存在的缝隙连接通道的特性。使用光学显微镜和电子显微镜根据形态学鉴定出四种不同的细胞类型（E、Fe、R和B）。虽然在B - B细胞对中无法测量连接电导（Gj），但在其他细胞类型的同源和异源组合中都分辨出了连接电流。E - E、Fe - Fe和E - Fe细胞对表现出对内向 - 外向电压（Vi - o）的强烈依赖性，使得Gj随着超极化增加，在约 - 40 mV时达到最大平台，并在去极化> 10 mV时消失。Gj - Vi - o关系可用平方玻尔兹曼关系描述，其中A = 0.101且V0 = 0.135 mV。在这个系统中，连接对跨连接电压的敏感性很轻微，如果确实存在的话。门控机制很复杂，有多种单通道电导状态的存在作为证据。单通道记录表明，在E - E、Fe - Fe和E - Fe细胞对之间通常发现大的单通道电导（> 200 pS），而在R - R细胞对之间检测到较小的通道尺寸（< 90 pS）。
