Light induced changes of internal pH in a barnacle photoreceptor and the effect of internal pH on the receptor potential

The Journal of Physiology
H M Brown, Robert Meech

Abstract

1. Intracellular pH (pH1) was measured in Balanus photoreceptors using pH-sensitive glass micro-electrodes. The average pH1 of twelve photoreceptors which had been dark adapted for at least 30 min was 7.3 +/- 0.07 (S.D.). 2. Illumination reduced the recorded pH1 by as much as 0.2 pH unit. The change in pH1 was graded with light intensity. 3. When the cells were exposed to CO2 in the dark, pH1 declined monophasically. Saline equilibrated with 2% CO2; 98% O2 produced a steady reduction in pH1 of about 0.25 unit in 2--3 min. The buffering capacity of the receptor cell cytoplasm calculated from such experiments is approximately 15 slykes. 4. In the presence of HCO3-1, CO2 saline produced smaller, biphasic changes in pH1. 5. The membrane depolarization produced by a bright flash (depolarizing receptor potential) was reversibly reduced in the presence of external CO2 or by injection of H+. Iontophoretic injection of HCO2- increased the amplitude of the receptor potential. 6. In individual cells there was a close correlation between the amplitude of the receptor potential and pH1. 7. Saline equilibrated with CO2 reduced the light induced current (recorded under voltage-clamp) by 40--50% without affecting its reversal potential. 8. Exp...Continue Reading

References

Jan 1, 1981·Progress in Biophysics and Molecular Biology·G L Fain, J E Lisman
Mar 1, 1984·Cellular and Molecular Neurobiology·J A Connor, Z Ahmed
Feb 1, 2013·Wiley Interdisciplinary Reviews. Membrane Transport and Signaling·Robert Meech
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Aug 1, 1986·Acta Physiologica Scandinavica·B Rydqvist, H M Brown
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Related Concepts

Photoreceptors
Buffers
Microelectrodes
Membrane
Protoplasm
Receptor Cell
Resting Potentials
AGXT gene
PDZK1 gene
Balanus

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