Light-induced calcium fluxes from outer segment layer of vertebrate retinas

Yoshikami, S.; George, John; Hagins, W. A.

doi:10.1038/286395a0

Cited by 187 publications

(89 citation statements)

References 22 publications

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“…These numbers show that the maximal capacity of Na-Ca exchange is about two orders of magnitude larger as compared with the light-induced Ca2+ efflux observed from r.o.s. in the functioning rod cell (Yoshikami et al 1980;Gold & Korenbrot, 1980). Ca2+ fluxes through a conductance mechanism were not detected at the low external Ca2+ concentrations (ftM) typical for the experiments in this study.…”

Section: Metabolic Requirements Of Ca2+ Fluxesmentioning

confidence: 87%

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Sodium‐calcium exchange in the outer segments of bovine rod photoreceptors.

Schnetkamp¹

1986

The Journal of Physiology

100

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SUMMARY1. Intact rod outer segments (r.o.s.) isolated from bovine retinas were used to measure net Ca2+ fluxes using the optical Ca2+ indicator Arsenazo III. Ca2+ fluxes were observed, which could change the internal Ca2+ content of isolated r.o.s. by as much as 0 5 mM s-5.2. The Ca2+ content of isolated intact r.o.s. was strongly dependent on the Na/Ca ratio in the isolation medium, and could be made less than 01 mol Ca2+ mold1 rhodopsin (zero Ca2+ in isolation medium) or up to 7 mol Ca2+ mold1 rhodopsin (zero Na+ in isolation medium).3. Ca2+ efflux from r.o.s. rich in Ca2+ was observed only when Na+ was added to the external medium (as opposed to any other alkali cation); in Ca2+-depleted r.o.s. Ca2+ uptake required the presence of internal Na+ and was inhibited selectively by external Na+. These results suggest that Na-Ca exchange across the plasma membrane operated freely in both directions and controlled the internal Ca2+ concentration in r.o.s.4. Na+-stimulated Ca2+ efflux depended on the external Na+ concentration in a sigmoidal way. This suggests that the simultaneous binding of two Na ions is rate limiting for transport.5. In Ca2+-depleted r.o.s. and in the absence of external Na+, 1 mol Ca2+ mold1 rhodopsin (or 3 mM-total Ca2+) could be taken up within 1 min by intact r.o.s. at a free external Ca2+ concentration of about 1 /tM. 6. Only part of the internal Ca2+ was available for Na-Ca exchange. The external Na+ and K+ concentration as well as the temperature were factors controlling the accessibility of internal Ca2+ to participate in Na-Ca exchange.7. Ca2+ fluxes in r.o.s. with a permeabilized plasma membrane but intact disk membranes were very similar to those observed in intact r.o.s.; Na-Ca exchange could operate in both directions across the disk membrane.8. In addition to Na-Ca exchange, leaky r.o.s. also showed a guanosine 3', 5'-cyclic monophosphate (cyclic GMP)-induced Ca2+ release that was about I of the rate of Present address:

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Section: Metabolic Requirements Of Ca2+ Fluxesmentioning

confidence: 87%

“…Similarly, the Na+ dependence of the light-induced Ca2+ release from r.o.s. in the retina suggests that this Ca2+ release is mediated by Na-Ca exchange (Yoshikami, George & Hagins, 1980;Gold & Korenbrot, 1980). In isolated r.o.s.…”

Section: Metabolic Requirements Of Ca2+ Fluxesmentioning

confidence: 99%

Sodium‐calcium exchange in the outer segments of bovine rod photoreceptors.

Schnetkamp¹

1986

The Journal of Physiology

100

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“…The morphological, biochemical, and electrophysiological interdependence of the neural retina and pigment epithelium has been demonstrated (33). Substances are known to be released from the retinal photoreceptors as has recently been shown in the case of a light-induced flux of calcium from the outer segment layer (34). The pigment epithelium is also known to respond to light-induced changes in the metabolism of the retina (35).…”

Section: Resultsmentioning

confidence: 99%

Retinal pigment epithelium contains a distinctive strychnine-binding site

Bae

et al. 1982

Neurochem Res

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Membranes prepared from the retinal pigment epithelium of several species possess a specific site which binds [ 3 H]strychnine. This binding has a somewhat lower affinity and a much greater density than the corresponding interaction in the hindbrain or ~eural retina. Binding is not greatly altered in the presence of 10-3 M glycine, L-alanine, 13-alanine, taurine, or serine. Thus, the receptor does not resemble the classical glycine receptor of the hindbrain and spinal cord. This new type of binding site appears to be confined to the pigment epithelial layer of the retina.

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“…Ca 2+ regulates the 'Na + -dark current' by binding reversibly to the plasma membrane sites through which the Na+ flows into the rod outer segment. They proposed no specific role for rhodopsin but an attractive possibility is that rhodopsin itself forms a transmembrane Ca 2+ channel (Yoshikami, George & Hagins, 1980).…”

Section: (Ii) Channelsmentioning

confidence: 99%

Functional reassembly of membrane proteins in planar lipid bilayers

Montal

Darszon

Schindler

1981

Quart. Rev. Biophys.

116

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Recent progress in membrane biology has brought us to a stage where it is possible to associate complex biological processes to identifiable membrane proteins. Technical advances in the biochemical characterization and purification of membrane proteins have contributed a wealth of structural information. The reconstitution approach has proved to be valuable in our efforts to understand the molecular mechanisms of membrane transport and energy transduction.

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Light-induced calcium fluxes from outer segment layer of vertebrate retinas

Cited by 187 publications

References 22 publications

Sodium‐calcium exchange in the outer segments of bovine rod photoreceptors.

Sodium‐calcium exchange in the outer segments of bovine rod photoreceptors.

Retinal pigment epithelium contains a distinctive strychnine-binding site

Functional reassembly of membrane proteins in planar lipid bilayers

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