PMID- 37738060
OWN - NLM
STAT- MEDLINE
DCOM- 20230925
LR  - 20240213
IS  - 1552-5783 (Electronic)
IS  - 0146-0404 (Print)
IS  - 0146-0404 (Linking)
VI  - 64
IP  - 12
DP  - 2023 Sep 1
TI  - A Simplified Model of Activation and Deactivation of Human Rod 
      Phototransduction-An Electroretinographic Study.
PG  - 36
LID - 10.1167/iovs.64.12.36 [doi]
LID - 36
AB  - PURPOSE: To test the hypothesis that a simple model having properties consistent 
      with activation and deactivation in the rod approximates the whole time course of 
      the photoresponse. METHODS: Routinely, an exponential of the form f = alpha.(1 - 
      exp(-(tau.(t - teff)s-1))), with amplitude alpha, rate constant tau (often scaled by 
      intensity), irreducible delay teff, and time exponent s-1, is fit to the early 
      period of the flash electroretinogram. Notably, s (an integer) represents the 
      three integrating stages in the rod amplification cascade (rhodopsin 
      isomerization, transducin activation, and cGMP hydrolysis). The time course of 
      the photoresponse to a 0.17 cd.s.m-2 conditioning flash (CF) was determined in 21 
      healthy eyes by presenting the CF plus a bright probe flash (PF) in tandem, 
      separated by interstimulus intervals (ISIs) of 0.01 to 1.4 seconds, and 
      calculating the proportion of the PF a-wave suppressed by the CF at each ISI. To 
      test if similar kinetics describe deactivation, difference of exponential (DoE) 
      functions with common alpha and teff parameters, respective rate constants for the 
      initiation (I) and quenching (Q) phases of the response, and specified values of 
      s (sI, sQ), were compared to the photoresponse time course. RESULTS: As 
      hypothesized, the optimal values of sI and sQ were 3 and 2, respectively. Mean +/- 
      SD alpha was 0.80 +/- 0.066, I was 7700 +/- 2400 m2.cd-1.s-3, and Q was 1.4 +/- 0.47 s-1. 
      Overall, r2 was 0.93. CONCLUSIONS: A method, including a DoE model with just 
      three free parameters (alpha, I, Q), that robustly captures the magnitude and 
      time-constants of the complete rod response, was produced. Only two steps 
      integrate to quench the rod photoresponse.
FAU - Akula, James D
AU  - Akula JD
AD  - Ophthalmology, Boston Children's Hospital, Boston, Massachusetts, United States.
AD  - Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States.
FAU - Lancos, Annie M
AU  - Lancos AM
AD  - Ophthalmology, Boston Children's Hospital, Boston, Massachusetts, United States.
FAU - AlWattar, Bilal K
AU  - AlWattar BK
AD  - Ophthalmology, Boston Children's Hospital, Boston, Massachusetts, United States.
AD  - Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States.
FAU - De Bruyn, Hanna
AU  - De Bruyn H
AD  - Ophthalmology, Boston Children's Hospital, Boston, Massachusetts, United States.
FAU - Hansen, Ronald M
AU  - Hansen RM
AD  - Ophthalmology, Boston Children's Hospital, Boston, Massachusetts, United States.
AD  - Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States.
FAU - Fulton, Anne B
AU  - Fulton AB
AD  - Ophthalmology, Boston Children's Hospital, Boston, Massachusetts, United States.
AD  - Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States.
LA  - eng
GR  - P50 HD105351/HD/NICHD NIH HHS/United States
GR  - R01 EY010597/EY/NEI NIH HHS/United States
GR  - R01 EY028953/EY/NEI NIH HHS/United States
PT  - Journal Article
PT  - Research Support, N.I.H., Extramural
PL  - United States
TA  - Invest Ophthalmol Vis Sci
JT  - Investigative ophthalmology & visual science
JID - 7703701
RN  - H2D2X058MU (Cyclic GMP)
SB  - IM
MH  - Humans
MH  - *Electroretinography
MH  - *Eye
MH  - Cognition
MH  - Cyclic GMP
MH  - Light Signal Transduction
PMC - PMC10528468
COIS- Disclosure: J.D. Akula, None; A.M. Lancos, None; B.K. AlWattar, None; H. De 
      Bruyn, None; R.M. Hansen, None; A.B. Fulton, None
EDAT- 2023/09/22 12:42
MHDA- 2023/09/25 06:43
PMCR- 2023/09/22
CRDT- 2023/09/22 11:33
PHST- 2023/09/25 06:43 [medline]
PHST- 2023/09/22 12:42 [pubmed]
PHST- 2023/09/22 11:33 [entrez]
PHST- 2023/09/22 00:00 [pmc-release]
AID - 2792777 [pii]
AID - IOVS-23-37787 [pii]
AID - 10.1167/iovs.64.12.36 [doi]
PST - ppublish
SO  - Invest Ophthalmol Vis Sci. 2023 Sep 1;64(12):36. doi: 10.1167/iovs.64.12.36.