Longitudinal spread of second messenger signals in isolated rod outer segments of lizards
Longitudinal spread of second messenger signals in isolated rod outer segments of lizards
复制标题
DOI：
10.1111/j.1469-7793.1999.0679n.x
复制
发表时间：
1999-09-01
影响因子：
5.5
通讯作者：
Detwiler, PB
中科院分区：
文献类型：
--
作者：
Gray-Keller, M;Denk, W;Detwiler, PB
1.在脊椎动物视杆细胞中，通过光激活光转导级联会触发至少两种可扩散的细胞内第二信使（cGMP和Ca 2+）浓度的变化，其作用取决于它们从其产生或进入部位扩散多远。为了解决其空间分布的问题，采用细胞贴附贴片电流记录和钙绿-葡聚糖荧光成像技术分别测量了在全细胞电压钳下，在功能完整的壁虎蜥蜴杆外节中cGMP和Ca 2+的纵向分布. cGMP和Ca 2+浓度的光诱发的变化衰减与距离的稳定的焦点激活的网站由双光子吸收1064 nm的光与类似的衰减长度为3.5 μ m。3.这些结果可以理解的基础上耦合扩散的细胞内信使的定量模型，这是可能有广泛的相关性，一般的第二信使信号通路。从一个稳定的局部照明的网站的适应的传播的衰减长度为约8 μ m，即基本上长于cGMP和Ca 2+的传播测量的衰减长度。然而，有许多因素可以扩大光反应的功能变化与扩散信使浓度之间的明显关系。由于这些原因，测量的衰减长度是适应扩展的上限估计，并且不排除Ca 2+和/或cGMP携带适应信号的可能性。
1. In vertebrate rods activation of the phototransduction cascade by light triggers changes in the concentrations of at least two diffusible intracellular second messengers (cGMP and Ca2+) whose actions depend on how far they spread from their site of production or entry. To address questions about their spatial spread, cell-attached patch current recording and fluorescence imaging of Calcium Green-dextran were used to measure the longitudinal spread of cGMP and Ca2+, respectively, in functionally intact isolated Gecko gecko lizard rod outer segments under whole-cell voltage clamp.2. The light-evoked changes in cGMP and Ca2+ concentrations decayed with distance from a site of steady focal activation by two-photon absorption of 1064 nm light with similar decay lengths of similar to 3.5 mu m.3. These results can be understood on the basis of a quantitative model of coupled diffusible intracellular messengers, which is likely to have broad relevance for second messenger signalling pathways in general.4. The decay length for the spread of adaptation from a site of steady local illumination was about 8 mu m, i.e. substantially longer than the decay lengths measured for the spread of cGMP and Ca2+. There are a number of factors, however, that could broaden the apparent relationship between functional changes in the light response and the concentration of a diffusible messenger. For these reasons the measured decay length is an upper limit estimate of the spread of adaptation and does not rule out the possibility that Ca2+ and/or cGMP carry the adaptation signal.