Abstract
Gametophyte cells of Phaeoceros laevis (L.) Prosk. have vacuole electric potentials (PDs) of about −175 millivolts; the steady PD is not affected by light but small transient PDs result after changing from light to darkness or darkness to light. The PD is more negative than the Nernst potentials for any of the permeating ions. Changes in the concentration of any one of the external ions between 0.1 and 10 mm have only a very small effect on the PD. Increases in external pH cause the PD to depolarize by a few millivolts. Azide, 2,4-dinitrophenol, and NH4Cl each cause rapid and reversible depressions of the PD; the effects of these agents are similar in magnitude in the light and in the dark. Anoxia depolarizes the PD by about 30 millivolts in the light and by about 60 millivolts in the dark. Ouabain and 3-(3,4-dichlorophenyl)-1,1-dimethylurea have no effects on the PD. It is concluded that the membrane potential is controlled by an electrogenic efflux pump, possibly for H+. It is also concluded that the source of energy for the pump is respiration and not photosynthesis.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Boron W. F., De Weer P. Intracellular pH transients in squid giant axons caused by CO2, NH3, and metabolic inhibitors. J Gen Physiol. 1976 Jan;67(1):91–112. doi: 10.1085/jgp.67.1.91. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hill A. E. Ion and water transport in limonium. II. Short-circuit analysis. Biochim Biophys Acta. 1967 Jul 3;135(3):461–465. doi: 10.1016/0005-2736(67)90035-1. [DOI] [PubMed] [Google Scholar]
- Richards J. L., Hope A. B. The role of protons in determining membrane electrical characteristics in Chara corallina. J Membr Biol. 1974;16(2):121–144. doi: 10.1007/BF01872410. [DOI] [PubMed] [Google Scholar]
- Saddler H. D. The membrane potential of Acetabularia mediterranea. J Gen Physiol. 1970 Jun;55(6):802–821. doi: 10.1085/jgp.55.6.802. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Spanswick R. M. Evidence for an electrogenic ion pump in Nitella translucens. I. The effects of pH, K + , Na + , light and temperature on the membrane potential and resistance. Biochim Biophys Acta. 1972 Oct 23;288(1):73–89. doi: 10.1016/0005-2736(72)90224-6. [DOI] [PubMed] [Google Scholar]