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Interactions Between Calcium and cGMP in Dialyzed Detached Retinal Rod Outer Segments

  • G. Rispoli
  • P. B. Detwiler
Part of the Research Reports in Physics book series (RESREPORTS)

Abstract

Detached rod outer segments dialyzed with standard internal solution supplemented with 5 mM ATP and 0.86 mM GTP support normal phototransduction and generate light responses with the same sensitivity, kinetics and adaptational behavior as intact rods. The recovery of the light response involves the inactivation of the transduction cascade and activation of guanylate cyclase by the fall in intracellular calcium that accompanies the closure of light-sensitive channels. Experiments were done to test the influence of changes in the calcium and/or cGMP content of the ATP, GTP supplemented dialysis solution on the light response. Response recovery was accelerated in outer segments dialyzed with high calcium solution. The amplitude of the Na-Ca exchange current in these cells was consistent with at least a five-fold increase in intracellular calcium. The acceleration of response recovery under these conditions is surprising because high internal calcium would be expected to slow rather than speed the activation of cyclase by a light-evoked decrease in calcium. The implication of this and other paradoxical results pertaining to the interaction between intracellular calcium and cGMP levels are discussed.

Keywords

Dark Current Outer Segment Guanylate Cyclase Light Response Dialysis Solution 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 1992

Authors and Affiliations

  • G. Rispoli
    • 1
  • P. B. Detwiler
    • 1
  1. 1.Department of Physiology & BiophysicsUniversity of Washington, School of MedicineSeattleUSA

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