Visual Neuroscience



Test of the paired-flash electroretinographic method in mice lacking b-waves


JENNIFER J. KANG  DERWENT  a1 a2 , SHANNON M.  SASZIK  a3 a4 , HIDETAKA  MAEDA  a3 a5 , DEBORAH M.  LITTLE  a6 , MACHELLE T.  PARDUE  a7 a8 , LAURA J.  FRISHMAN  a3 and DAVID R.  PEPPERBERG  a1 c1
a1 Lions of Illinois Eye Research Institute, Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, College of Medicine, Chicago, Illinois
a2 Department of Biomedical Engineering, Pritzker Institute of Biomedical Science and Engineering, Illinois Institute of Technology, Chicago, Illinois
a3 College of Optometry, University of Houston, Houston, Texas
a4 Department of Ophthalmology, Northwestern University School of Medicine, Chicago, Illinois
a5 Kobe University Medical School, Kobe, Japan
a6 Department of Neurology and Rehabilitation, and Center for Cognitive Medicine, University of Illinois at Chicago, College of Medicine, Chicago, Illinois
a7 Atlanta VA Medical Center, Decatur, Georgia
a8 Department of Ophthalmology, Emory University, Atlanta, Georgia

Article author query
derwent jjk   [Google Scholar] 
saszik sm   [Google Scholar] 
maeda h   [Google Scholar] 
little dm   [Google Scholar] 
pardue mt   [Google Scholar] 
frishman lj   [Google Scholar] 
pepperberg dr   [Google Scholar] 
 

Abstract

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 [similar]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.

(Received September 27 2006)
(Accepted February 14 2007)


Key Words: Rod photoreceptor; Electroretinogram; Paired-flash ERG; nob mouse.

Correspondence:
c1 Address correspondence and reprint requests to: David R. Pepperberg, Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, 1855 W. Taylor St., Chicago, IL 60612, USA. E-mail: davipepp@uic.edu