Kang Derwent Jennifer J, Saszik Shannon M, Maeda Hidetaka, Little Deborah M, Pardue Machelle T, Frishman Laura J, Pepperberg David R
Lions of Illinois Eye Research Institute, Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, College of Medicine, Chicago, Illinois 60612, USA.
Vis Neurosci. 2007 Mar-Apr;24(2):141-9. doi: 10.1017/S0952523807070162.
Previous studies of rod photoreceptors in vivo have employed a paired-flash electroretinographic (ERG) technique to determine rod response properties. To test whether absence versus presence of the ERG b-wave affects the photoreceptor response derived by the paired-flash method, we examined paired-flash-derived responses obtained from nob mice, a mutant strain with a defect in signal transduction between photoreceptors and ON bipolar cells that causes a lack of the b-wave. Normal littermates of the nob mice served as controls. The normalized amplitude-intensity relation of the derived response determined in nob mice at the near-peak time of 86 ms was similar to that determined for the controls. The full time course of the derived rod response was obtained for test flash strengths ranging from 0.11 to 17.38 scotopic cd s m(-2) (sc cd s m(-2)). Time-course data obtained from nob and control mice exhibited significant but generally modest differences. With saturating test flash strengths, half-recovery times for the derived response of nob versus control mice differed by approximately 60 ms or less about the combined (nob and control) average respective values. Time course data also were obtained before versus after intravitreal injection of L-2-amino-4-phosphonobutyrate (APB) (which blocks transmission from photoreceptors to depolarizing bipolar cells) and of cis 2,3-piperidine dicarboxylic acid (PDA) (which blocks transmission to OFF bipolar cells, and to horizontal, amacrine and ganglion cells). Neither APB nor PDA substantially affected derived responses obtained from nob or control mice. The results provide quantitative information on the effect of b-wave removal on the paired-flash-derived response in mouse. They argue against a substantial skewing effect of the b-wave on the paired-flash-derived response obtained in normal mice and are consistent with the notion that, to good approximation, this derived response represents the isolated flash response of the photoreceptors in both nob and normal mice.
以往对活体视杆光感受器的研究采用了双闪光视网膜电图（ERG）技术来确定视杆细胞的反应特性。为了测试ERG b波的有无是否会影响双闪光法得出的光感受器反应，我们检测了从nob小鼠获得的双闪光衍生反应，nob小鼠是一种突变品系，其光感受器与ON双极细胞之间的信号转导存在缺陷，导致缺乏b波。nob小鼠的正常同窝小鼠作为对照。在86毫秒的近峰值时间，在nob小鼠中确定的衍生反应的归一化幅度-强度关系与对照组相似。对于从0.11到17.38 scotopic cd s m(-2)（sc cd s m(-2)）的测试闪光强度范围，获得了衍生视杆反应的完整时间进程。从nob小鼠和对照小鼠获得的时间进程数据显示出显著但通常较小的差异。在饱和测试闪光强度下，nob小鼠与对照小鼠衍生反应的半恢复时间在（nob和对照）各自合并平均值附近相差约60毫秒或更少。还在玻璃体内注射L-2-氨基-4-膦酰丁酸（APB）（阻断从光感受器到去极化双极细胞的传递）和顺式2,3-哌啶二羧酸（PDA）（阻断到OFF双极细胞以及水平细胞、无长突细胞和神经节细胞的传递）之前和之后获得了时间进程数据。APB和PDA均未实质性影响从nob小鼠或对照小鼠获得的衍生反应。结果提供了关于去除b波对小鼠双闪光衍生反应影响的定量信息。它们反对b波对正常小鼠中获得的双闪光衍生反应有实质性的偏差影响，并且与这样的观点一致，即大致上，这种衍生反应代表了nob小鼠和正常小鼠中光感受器的孤立闪光反应。
