Response sensitivity and voltage gain of the rod- and cone-bipolar cell synapses in dark-adapted tiger salamander retina.
Response sensitivity and voltage gain of the rod- and cone-bipolar cell synapses in dark-adapted tiger salamander retina.
复制标题
暗适应虎蝾螈视网膜中杆状和锥状双极细胞突触的响应灵敏度和电压增益。
DOI：
10.1152/jn.1997.78.5.2662
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
Wu,SM
中科院分区：
文献类型：
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作者：
Yang,XL;Wu,SM
杨雄利，Samuel M. Wu。虎蝾螈视网膜杆状和锥状双极细胞突触的响应灵敏度和电压增益。中国生物医学工程学报，2009,31(2):557 - 557。在黑暗适应条件下，在虎蝾螈幼体Ambystoma tigrinum的分离视网膜上记录了棒状细胞、视锥细胞和双极细胞。列出了24个视杆细胞、15个视锥细胞和41个双极细胞在不同强度500 nm光阶下的电压响应，并用双曲函数拟合，估计了它们的阶跃灵敏度和相对灵敏度（log σ）。在线性响应强度范围内，杆状体SS（棒）的阶跃灵敏度为- 1.0 mV光子−1μm2s或0.034 mV Rh*−1s棒；锥状体SS（锥）的阶跃灵敏度为- 0.00146 mV光子−1μm2s或0.000048 mV Rh*−1s棒。杆状体和锥状体的响应相对均匀，响应幅度和灵敏度变化不大。相比之下，双极细胞的反应是异质的，反应幅度和灵敏度变化很大。双极电池的最大响应幅度在5 ~ 25mv之间，相对响应灵敏度（log σ）在- 8.11 ~ - 2.32之间变化。双极电池在线性响应强度范围内的阶跃灵敏度为0.0000438 ~ 51.82 mV光子−1μm2s。暗适应虎蝾螈视网膜的双极性细胞根据其相对灵敏度分为两组，很少有细胞落在中等光强区域。混合双极电池（dbcommand和HBCM）的相对响应灵敏度为−8.11 ~−5.54，阶跃灵敏度为1.22 ~ 51.82 mV光子−1μm2s。锥驱动双极细胞（dbcc和HBCC）的相对响应灵敏度为−3.45 ~−2.32，阶跃灵敏度为0.0000438 ~ 0.00201 mV光子-1μm2sec。杆状- dbccor杆状- hbccmsynaptic在杆状暗膜电位附近的弦电压增益范围为1.14 ~ 48.43，锥体- dbccor锥体- hbccsynaptic在锥体暗膜电位附近的弦电压增益范围为0.03 ~ 1.38。在杆状或锥状暗膜电位附近发现了最高的电压增益。我们利用线性减法研究了从锥细胞到5个混合双极细胞的突触输入，发现每个双极细胞中锥突触的电压增益与杆突触的电压增益非常接近。这一结果表明，虽然混合双极细胞的反应主要由杆状细胞介导，但它们对长波光（>650 nm）的反应同时由杆状细胞和锥状细胞介导，并且突触增益相当。讨论了混合型和锥驱动型双极细胞在适应黑暗视网膜信息处理中的功能作用。
Yang, Xiong-Li and Samuel M. Wu.Response sensitivity and voltage gain of the rod- and cone-bipolar cell synapses in dark-adapted tiger salamander retina.J. Neurophysiol.78: 2662–2673, 1997. Rods, cones, and bipolar cells were recorded in superfused, flat-mounted isolated retinas of the larval tiger salamander,Ambystoma tigrinum,under dark-adapted conditions. Voltage responses of 24 rods, 15 cones, and 41 bipolar cells in dark-adapted retinas to 500 nm light steps of various intensities were listed and fitted with hyperbolic functions, and their step sensitivities and relative sensitivities (log σ) were estimated. In the linear response-intensity ranges, the step sensitivity of rods,SS(rod), is −1.0 mV photon−1μm2s or 0.034 mV Rh*−1s rod and that of the cones,SS(cone), is ∼0.00146 mV photon−1μm2s or 0.000048 mV Rh*−1s rod. The rod and cone responses were relatively homogenous with little variations in response amplitude and sensitivity. In contrast, bipolar cell responses were heterogenous with large variations in response amplitude and sensitivity. The maximum response amplitude of bipolar cells varied from 5 to 25 mV, and the relative response sensitivity (log σ) varied >6 log units (−8.11 to −2.32). The step sensitivity of bipolar cells in the linear response-intensity range varied from 0.0000438 to 51.82 mV photon−1μm2s. Bipolar cells in dark-adapted tiger salamander retinas fell into two groups according to their relative sensitivities with very few cells falling in the intermediate light intensity region. The mixed bipolar cells (DBCMand HBCM) exhibited relative response sensitivity ranged from −8.11 to −5.54, and step sensitivity ranged from 1.22 to 51.82 mV photon−1μm2s. The cone-driven bipolar cells (DBCCand HBCC) exhibited relative response sensitivity ranged from −3.45 to −2.32, and step sensitivity ranged from 0.0000438 to 0.00201 mV photon-1μm2sec. The chord voltage gain of the rod-DBCMor rod-HBCMsynapses near the rod dark membrane potential ranged from 1.14 to 48.43 and that of the cone-DBCCor cone-HBCCsynaptic gain near the cone dark membrane potential ranged from 0.03 to 1.38. The highest voltage gains were found near the rod or cone dark membrane potentials. By the use of linear subtraction method, we studied the synaptic inputs from cones to five mixed bipolar cells, and the voltage gains of the cone synapses in each of the bipolar cells were very close to the voltage gain of the rod synapses. This result suggests that although the responses of mixed bipolar cells are mediated mainly by rods when lights of short and medium wavelengths are used, their responses to long wavelength lights (>650 nm) are mediated by both rods and cones with comparable synaptic gains. Functional roles of the mixed and cone-driven bipolar cells in information processing in dark-adapted retinas are discussed.