Abstract
Squid giant axons were perfused intracellularly with solutions containing various kinds of proteases (1 mg/ml). Except for a 10 µ layer inside the axolemma the axoplasm was removed by a 5 min perfusion with Bacillus protease, strain N' (BPN'). The resting and action potentials were unchanged and the axon maintained its excitability for more than 4 hr on subsequent enzyme-free perfusion. After perfusion with protease solution for 30 min the axoplasm was almost completely removed. The excitability was maintained, but the action potential became prolonged and rapidly developed a plateau of several hundred milliseconds. The change was not reversible even when the enzyme was removed from the perfusing fluid. Two other enzymes, prozyme and bromelin, also removed the protoplasm without blocking conduction. Trypsin suppressed within 3 min the excitability of the axon. It is suggested that the proteases alter macromolecules in the excitable membrane and thus affect the shape of the action potential.
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.
- BAKER P. F., HODGKIN A. L., MEVES H. THE EFFECT OF DILUTING THE INTERNAL SOLUTION ON THE ELECTRICAL PROPERTIES OF A PERFUSED GIANT AXON. J Physiol. 1964 Apr;170:541–560. doi: 10.1113/jphysiol.1964.sp007348. [DOI] [PMC free article] [PubMed] [Google Scholar]
- BAKER P. F., HODGKIN A. L., SHAW T. I. Replacement of the axoplasm of giant nerve fibres with artificial solutions. J Physiol. 1962 Nov;164:330–354. doi: 10.1113/jphysiol.1962.sp007025. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Freeman A. R., Reuben J. P., Brandt P. W., Grundfest H. Osmometrically determined characteristics of the cell membrane of squid and lobster giant axons. J Gen Physiol. 1966 Nov;50(2):423–445. doi: 10.1085/jgp.50.2.423. [DOI] [PMC free article] [PubMed] [Google Scholar]
- LUFT J. H. Improvements in epoxy resin embedding methods. J Biophys Biochem Cytol. 1961 Feb;9:409–414. doi: 10.1083/jcb.9.2.409. [DOI] [PMC free article] [PubMed] [Google Scholar]
- MOORE J. W., NARAHASHI T., ULBRICHT W. SODIUM CONDUCTANCE SHIFT IN AN AXON INTERNALLY PERFUSED WITH A SUCROSE AND LOW-POTASSIUM SOLUTION. J Physiol. 1964 Aug;172:163–173. doi: 10.1113/jphysiol.1964.sp007410. [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]
- TASAKI I., HAGIWAR A. S. Demonstration of two stable potential states in the squid giant axon under tetraethylammonium chloride. J Gen Physiol. 1957 Jul 20;40(6):859–885. doi: 10.1085/jgp.40.6.859. [DOI] [PMC free article] [PubMed] [Google Scholar]
- TASAKI I., TAKENAKA T. EFFECTS OF VARIOUS POTASSIUM SALTS AND PROTEASES UPON EXCITABILITY OF INTRACELLULARLY PERFUSED SQUID GIANT AXONS. Proc Natl Acad Sci U S A. 1964 Sep;52:804–810. doi: 10.1073/pnas.52.3.804. [DOI] [PMC free article] [PubMed] [Google Scholar]
- TOBIAS J. M. Effects of phospholipases, collagenase and chymotrypsin on impulse conduction and resting potential in the lobster axon with parallel experiments on frog muscle. J Cell Physiol. 1955 Oct;46(2):183–207. doi: 10.1002/jcp.1030460203. [DOI] [PubMed] [Google Scholar]
- Tasaki I., Singer I., Takenaka T. Effects of internal and external ionic environment on excitability of squid giant axon. A macromolecular approach. J Gen Physiol. 1965 Jul;48(6):1095–1123. doi: 10.1085/jgp.48.6.1095. [DOI] [PMC free article] [PubMed] [Google Scholar]