Test of the paired-flash electroretinographic method in mice lacking b-waves.
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.
Kang Derwent
Jennifer J
JJ
Lions of Illinois Eye Research Institute, Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, College of Medicine, Chicago, Illinois 60612, USA.
Saszik
Shannon M
SM
Maeda
Hidetaka
H
Little
Deborah M
DM
Pardue
Machelle T
MT
Frishman
Laura J
LJ
Pepperberg
David R
DR
D000465:Algorithms; D000613:Aminobutyrates / Q000494:pharmacology; D000818:Animals; D004307:Dose-Response Relationship, Radiation; D004596:Electroretinography / Q000187:drug effects / Q000528:radiation effects; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D008029:Lighting; D008297:Male; D051379:Mice; D008817:Mice, Mutant Strains / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D010875:Pipecolic Acids / Q000494:pharmacology; D011509:Proteoglycans / Q000235:genetics; D017948:Retinal Rod Photoreceptor Cells / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D013997:Time Factors
D000613:Aminobutyrates; D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D010875:Pipecolic Acids; D011509:Proteoglycans; C029262:2,3-piperidinedicarboxylic acid; C012729:2-amino-4-phosphonobutyric acid