December 2002
Volume 43, Issue 13
ARVO Annual Meeting Abstract  |   December 2002
Nitric Oxide as a Light Adapting Signal in Cone Photoreceptors of the Turtle Retina
Author Affiliations & Notes
  • H Levy
    Physiology Isreal Instit of Technology Haifa Israel
  • G Twig
    Haifa Israel
  • I Perlman
    Haifa Israel
  • Footnotes
    Commercial Relationships   H. Levy, None; G. Twig, None; I. Perlman, None.
Investigative Ophthalmology & Visual Science December 2002, Vol.43, 3751. doi:
  • Views
  • Share
  • Tools
    • Alerts
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      H Levy, G Twig, I Perlman; Nitric Oxide as a Light Adapting Signal in Cone Photoreceptors of the Turtle Retina . Invest. Ophthalmol. Vis. Sci. 2002;43(13):3751.

      Download citation file:

      © ARVO (1962-2015); The Authors (2016-present)

  • Supplements

Abstract: : Purpose: Nitric Oxide (NO) has been identified to play an important role in inter-cellular communication in different tissues. In the retina, numerous cells were found to contain Nitric Oxide Synthase (NOS), the enzyme that synthesizes NO from L-arginine. In this study, we examined the modulatory effects of NO upon the distal retina of the turtle under different adaptation conditions, in order to test the suggestion that NO acts as a light adapting signal. Methods: The photoresponses of cone photoreceptors were recorded in the everted eyecup preparation of the turtle Mauremys caspica. Light stimuli of different intensities were applied in the dark-adapted state and during background illumination with different intensities. The intensity-response curve was fitted to a hyperbolic function in order to derive the maximal amplitude (Vmax) and semi-saturation constant (s). Retinal level of NO was modified by adding L-arginine, the substrate for NO synthesis or L-NAME, an inhibitor of NO synthesis. Sodium nitroprusside (SNP) was uesd as an exogenous donor of NO. Results: When a background light was turned on the cone photoreceptors initially hyperpolarized to reach a peak level and then gradually recovered to on intermediate potential. The degree of recovery was increased as the retinal level of NO was raised either by endogenous synthesis or by exogenous application. In a given state of adaptation, raising NO level in the retina caused augmentation of the cone photoresponses, while of the cones while inhibition of NO synthesis induced a decrease of the photoresponses. The effects of L-arginine and SNP were decreased as the level of background illumination was raised, while the effects of L-NAME did not change or even increased. Conclusion: Our findings are consistent with the notion that the rate of NO synthesis in the outer retina of the turtle is directly related to the intensity of ambient. The effects of NO upon the response of the cones to turning on a background light indicate that NO speeds up the rate at which turtle cones adapt to bright backgrounds.

Keywords: 491 nitric oxide • 517 photoreceptors • 384 dark/light adaptation 

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.