Abstract
A method has been developed which allows a length of electrically excitable squid axon to be internally dialyzed against a continuously flowing solution of defined composition. Tests showed that diffusional exchange of small molecules in the axoplasm surrounding the dialysis tube occurred with a half-time of 2–5 min, and that protein does not cross the wall of the dialysis tube. The composition of the dialysis medium was (mM): K isethionate 151, K aspartate 151, taurine 275, MgCI2 4–10, NaCl 80, KCN 2, EDTA 0.1, ATP 5–10, and phosphoarginine 0–10. The following measurements were made: resting Na influx 57 pmole/cm2sec (n = 8); resting potassium efflux 59 pmole/ cm2sec (n = 4); stimulated Na efflux 3.1 pmole/cm2imp (n = 9); stimulated K efflux 2.9 pmole/cm2imp (n = 3); resting Na efflux 48 pmole/cm2sec (n = 18); Q 10 Na efflux 2.2 (n = 5). Removal of ATP and phosphoarginine from the dialysis medium (n = 4) or external application of strophanthidin (n = 1) reversibly reduced Na efflux to 10–13 pmole/cm2sec. A general conclusion from the study is that dialyzed squid axons have relatively normal passive permeability properties and that a substantial fraction of the Na efflux is under metabolic control although the Na extrusion mechanism may not be working perfectly.
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Selected References
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- Adelman W. J., Jr, Dyron F. M., Senft J. P. Internally perfused axons: effects of two different anions on ionic conductance. Science. 1966 Mar 18;151(3716):1392–1394. doi: 10.1126/science.151.3716.1392. [DOI] [PubMed] [Google Scholar]
- BONTING S. L., CARAVAGGIO L. L. Sodium-potassium-activated adenosine triphosphatase in the squid giant axon. Nature. 1962 Jun 23;194:1180–1181. doi: 10.1038/1941180a0. [DOI] [PubMed] [Google Scholar]
- BRINLEY F. J., Jr, MULLINS L. J. ION FLUXES AND TRANSFERENCE NUMBER IN SQUID AXONS. J Neurophysiol. 1965 May;28:526–544. doi: 10.1152/jn.1965.28.3.526. [DOI] [PubMed] [Google Scholar]
- CALDWELL P. C., HODGKIN A. L., KEYNES R. D., SHAW T. I. THE RATE OF FORMATION AND TURNOVER OF PHOSPHORUS COMPOUNDS IN SQUID GIANT AXONS. J Physiol. 1964 May;171:119–131. doi: 10.1113/jphysiol.1964.sp007366. [DOI] [PMC free article] [PubMed] [Google Scholar]
- CALDWELL P. C., HODGKIN A. L., KEYNES R. D., SHAW T. L. The effects of injecting 'energy-rich' phosphate compounds on the active transport of ions in the giant axons of Loligo. J Physiol. 1960 Jul;152:561–590. doi: 10.1113/jphysiol.1960.sp006509. [DOI] [PMC free article] [PubMed] [Google Scholar]
- CALDWELL P. C., KEYNES R. D. The permeability of the squid giant axon to radioactive potassium and chloride ions. J Physiol. 1960 Nov;154:177–189. doi: 10.1113/jphysiol.1960.sp006572. [DOI] [PMC free article] [PubMed] [Google Scholar]
- DEFFNER G. G. The dialyzable free organic constituents of squid blood; a comparison with nerve axoplasm. Biochim Biophys Acta. 1961 Feb 18;47:378–388. doi: 10.1016/0006-3002(61)90298-0. [DOI] [PubMed] [Google Scholar]
- HODGKIN A. L., KEYNES R. D. Experiments on the injection of substances into squid giant axons by means of a microsyringe. J Physiol. 1956 Mar 28;131(3):592–616. doi: 10.1113/jphysiol.1956.sp005485. [DOI] [PMC free article] [PubMed] [Google Scholar]
- HOFFMAN J. F. Physiological characteristics of human red blood cell ghosts. J Gen Physiol. 1958 Sep 20;42(1):9–28. doi: 10.1085/jgp.42.1.9. [DOI] [PMC free article] [PubMed] [Google Scholar]
- OIKAWA T., SPYROPOULOS C. S., TASAKI I., TEORELL T. Methods for perfusing the giant axon of Loligo pealii. Acta Physiol Scand. 1961 Jun;52:195–196. doi: 10.1111/j.1748-1716.1961.tb02218.x. [DOI] [PubMed] [Google Scholar]
- SHANES A. M., BERMAN M. D. Kinetics of ion movement in the squid giant axon. J Gen Physiol. 1955 Nov 20;39(2):279–300. doi: 10.1085/jgp.39.2.279. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Shaw T. I. Cation movements in perfused giant axons. J Physiol. 1966 Jan;182(1):209–216. doi: 10.1113/jphysiol.1966.sp007819. [DOI] [PMC free article] [PubMed] [Google Scholar]
- TASAKI I. Permeability of squid axon membrane to various ions. J Gen Physiol. 1963 Mar;46:755–772. doi: 10.1085/jgp.46.4.755. [DOI] [PMC free article] [PubMed] [Google Scholar]