Modeling the current-voltage characteristics of charophyte membranes.: II.: The effect of salinity on membranes of Lamprothamnium papulosum
Modeling the current-voltage characteristics of charophyte membranes.: II.: The effect of salinity on membranes of Lamprothamnium papulosum
复制标题
DOI：
10.1007/pl00020977
复制
发表时间：
2001-05-15
影响因子：
2.4
通讯作者：
Shepherd, VA
中科院分区：
文献类型：
--
作者：
Beilby, MJ;Shepherd, VA
Lamprothamalphae是一种耐盐轮藻，栖息在广泛的盐环境。在不同盐度的海水环境中（全海水、0.5SW、0.4SW和0.2SW），模拟了亮球藻细胞膜的电特性，并对细胞进行了电压钳位，得到了细胞膜的IN（电流-电压）和GN（电导-电压）曲线。在不同盐度下生长的细胞表现出三种类型的IN分布（状态）之一：泵状态、背景状态和K+状态。本研究集中在泵和背景状态。弯曲（泵为主）的I/V特性被发现在细胞与静息膜PD（电位差）-219 +/- 12 mV（0.2 SW：6个细胞，16个曲线），-161 +/- 12 mV（0.4 SW：6个细胞，7个曲线），-151 +/- 12 mV（0.5 SW：6个电池，12个剖面）和-137 +/- 12 mV全SW：8个电池，13个剖面）。在静止PD为-107 +/-12 mV（0.4 SW：7个细胞，12个剖面）、-108 +/-12 mV（0.5 SW：7个细胞，10个剖面）和-104 +/-12 mV（全SW：3个细胞，5个剖面）的细胞中发现了背景态的线性I/V特性。细胞的静息电导率（G）随着盐度的增加而逐渐增加，从0.5 S.m（-2）（0.2 SW）增加到22.0 S.m（-2）（全SW）。泵峰值电导仅从2 S.m（-2）（0.2 SW）上升到5 S.m（-2）（全SW），说明在盐浓度更高的培养基中观察到的去极化静息PD增加。I/V曲线的建模将内向K+整流器确定为对高渗激发的早期电反应。
Lamprothamnium is a salt-tolerant charophyte that inhabits a broad range of saline environments. The electrical characteristics of Lamprothamnium cell membranes were modeled in environments of different salinity: full seawater (SW), 0.5 SW, 0.4 SW, and 0.2 SW. The cells were voltage-clamped to obtain the IN (current-voltage) and GN (conductance-voltage) profiles of the cell membranes. Cells growing at the different salinities exhibited one of three types of IN profiles (states), pump-, background- and K+-states. This study concentrates on the pump- and background-states. Curved (pump-dominated) I/V characteristics were found in cells with resting membrane PDs (potential differences) of -219 +/- 12 mV tin 0.2 SW: 6 cells, 16 profiles), -161 +/- 12 mV tin 0.4 SW: 6 cells, 7 profiles), -151 +/- 12 mV tin 0.5 SW: 6 cells, 12 profiles) and -137 +/- 12 mV tin full SW: 8 cells, 13 profiles). The linear I/V charac- teristics of the background-state were found in cells with resting PDs of -107 +/- 12 mV tin 0.4 SW: 7 cells, 12 profiles), -108 +/- 12 mV tin 0.5 SW: 7 cells, 10 profiles) and -104 +/- 12 mV tin full SW: 3 cells, 5 profiles). The resting conductance (G) of the cells progressively increased with salinity, from 0.5 S.m(-2) (in 0.2 SW) to 22.0 S.m(-2) tin full SW). The pump peak conductance only rose from 2 S.m(-2) (0.2 SW) to 5 S.m(-2) (full SW), accounting for the increasingly depolarized resting PD observed in cells in more saline media.Upon exposure to hypertonic medium, both the pump and an inward K+ rectifier were stimulated. The modeling of the I/V profiles identified the inward K+ rectifier as an early electrical response to hypertonic challenge.