PMID: 2512177Nov 1, 1989Paper

EGTA modulates equatorial currents in frog lenses

Experimental Eye Research
S P Walsh, J W Patterson

Abstract

A combination of a vibrating probe with microelectrodes was used to study the effects on the equatorial K+ current, J, of perturbing the frog lens by removing Ca2+ from the bathing medium. The results were different in the absence and presence of EGTA. In the absence of EGTA the reversal potential (PDJ = 0) remained near the Nernst potential; the input resistance, R, and the resistance of the segment of the K+ current loop being studied, RJ, decreased; the driving force (PD - PDJ = 0) increased; and J increased fourfold. In the presence of EGTA J did not increase more than twofold; the current-voltage relationship became linear; RJ did not decrease and both the PD and the reversal potential, PDJ = 0, became less negative with time. These findings, which are dependent on the use of the vibrating probe, were unexpected, and they were explored by studying the effects of removing Na+ from the medium. Substituting TMA for Na+ did not increase J. Removal of Ca2+ and the addition of EGTA to a Na+-free medium in which frog lenses were bathed resulted in a decrease in RJ, and an increase in J; J varied inversely with the concentration of Na+ in the medium. The changes were reversible. A mechanism to account for the changes is proposed.

References

May 1, 1978·The Journal of General Physiology·N A Delamere, C A Paterson
Apr 1, 1985·Current Eye Research·J L Rae
Jul 1, 1985·Quarterly Journal of Experimental Physiology : an International Journal of the Physiological Society·T J JacobG Duncan
Feb 1, 1988·Experimental Eye Research·B E WindJ W Patterson
Jan 1, 1988·Ophthalmic Research·J W Patterson
Nov 1, 1974·The Journal of Cell Biology·L F Jaffe, R Nuccitelli
Nov 1, 1972·The Journal of General Physiology·F Bezanilla, C M Armstrong

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Citations

Oct 25, 2011·Progress in Retinal and Eye Research·Min ZhaoBrian Reid

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