Abstract
Determinants of 45Ca influx, 45Ca efflux, and 22Na efflux were examined in dog red blood cells. 45Ca influx is strongly influenced by the Na concentration on either side of the membrane, being stimulated by intracellular Na and inhibited by extracellular Na. A saturation curve is obtained when Ca influx is plotted as a function of medium Ca concentration. The maximum Ca influx is a function of pH (increasing with greater alkalinity) and cell volume (increasing with cell swelling). Quinidine strongly inhibits Ca influx. Efflux of 45Ca is stimulated by increasing concentrations of extracellular Na. 22Na efflux is stimulated by either Ca or Na in the medium, and the effects of the two ions are mutually exclusive rather than additive. Quinidine inhibits Ca-activated 22Na efflux. The results are considered in terms of a model for Ca-Na exchange, and it is concluded that the system shows many features of such a coupled ion transport system. However, the stoichiometric ratio between Ca influx and Ca-dependent Na efflux is highly variable under different experimental conditions. Because the Ca fluxes may reflect a combination of ATP-dependent, outward transport and Na-linked passive movements, the true stoichiometry of an exchanger may not be ascertainable in the absence of a specific Ca pump inhibitor. The meaning of these observations for Ca-dependent volume regulation by dog red blood cells is discussed.
Full Text
The Full Text of this article is available as a PDF (1.0 MB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Armando-Hardy M., Ellory J. C., Ferreira H. G., Fleminger S., Lew V. L. Inhibition of the calcium-induced increase in the potassium permeability of human red blood cells by quinine. J Physiol. 1975 Aug;250(1):32P–33P. [PubMed] [Google Scholar]
- Baker P. F., Blaustein M. P., Hodgkin A. L., Steinhardt R. A. The influence of calcium on sodium efflux in squid axons. J Physiol. 1969 Feb;200(2):431–458. doi: 10.1113/jphysiol.1969.sp008702. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Blaustein M. P. The interrelationship between sodium and calcium fluxes across cell membranes. Rev Physiol Biochem Pharmacol. 1974;70:33–82. doi: 10.1007/BFb0034293. [DOI] [PubMed] [Google Scholar]
- Davson H. The haemolytic action of potassium salts. J Physiol. 1942 Nov 30;101(3):265–283. doi: 10.1113/jphysiol.1942.sp003981. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Harrow J. A., Dhalla N. S. Effects of quinidine on calcium transport activities of the rabbit heart mitochondria and sarcotubular vesicles. Biochem Pharmacol. 1976 Apr 15;25(8):897–902. doi: 10.1016/0006-2952(76)90311-7. [DOI] [PubMed] [Google Scholar]
- Hoffman J. F., Laris P. C. Determination of membrane potentials in human and Amphiuma red blood cells by means of fluorescent probe. J Physiol. 1974 Jun;239(3):519–552. doi: 10.1113/jphysiol.1974.sp010581. [DOI] [PMC free article] [PubMed] [Google Scholar]
- OMACHI A., MARKEL R. P., HEGARTY H. Ca45 uptake by dog erythrocytes suspended in sodium and potassium chloride solutions. J Cell Comp Physiol. 1961 Apr;57:95–100. doi: 10.1002/jcp.1030570206. [DOI] [PubMed] [Google Scholar]
- PORTZEHL H., CALDWELL P. C., RUEEGG J. C. THE DEPENDENCE OF CONTRACTION AND RELAXATION OF MUSCLE FIBRES FROM THE CRAB MAIA SQUINADO ON THE INTERNAL CONCENTRATION OF FREE CALCIUM IONS. Biochim Biophys Acta. 1964 May 25;79:581–591. doi: 10.1016/0926-6577(64)90224-4. [DOI] [PubMed] [Google Scholar]
- Parker J. C. Dog red blood cells. Adjustment of density in vivo. J Gen Physiol. 1973 Feb;61(2):146–157. doi: 10.1085/jgp.61.2.146. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Parker J. C., Gitelman H. J., Glosson P. S., Leonard D. L. Role of calcium in volume regulation by dog red blood cells. J Gen Physiol. 1975 Jan;65(1):84–96. doi: 10.1085/jgp.65.1.84. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Parker J. C. Metabolism of external adenine nucleotides by human red blood cells. Am J Physiol. 1970 Jun;218(6):1568–1574. doi: 10.1152/ajplegacy.1970.218.6.1568. [DOI] [PubMed] [Google Scholar]
- Parker J. C., Snow R. L. Influence of external ATP on permeability and metabolism of dog red blood cells. Am J Physiol. 1972 Oct;223(4):888–893. doi: 10.1152/ajplegacy.1972.223.4.888. [DOI] [PubMed] [Google Scholar]
- Schatzmann H. J., Vincenzi F. F. Calcium movements across the membrane of human red cells. J Physiol. 1969 Apr;201(2):369–395. doi: 10.1113/jphysiol.1969.sp008761. [DOI] [PMC free article] [PubMed] [Google Scholar]