Abstract
The electroplaques of Astroscopus y-graecum were studied in situ with microelectrode recordings. Despite the distant taxonomic relations and the different origins of the organs, their properties in the teleost and torpedine marine electric fishes are remarkably similar. Only the innervated membrane (the dorsal) is electrogenically reactive in Astroscopus, and it, too, does not respond to electrical stimuli. As in the torpedine fishes, the uninnervated membrane of the electroplaques offers a very low resistance to the discharge of the innervated membrane. Additional direct evidence for electrical inexcitability of the reactive surface was obtained by denervating one of the bilateral organs. The denervated one did not respond to strong electrical stimuli which evoked responses in the opposite, innervated organ. The denervated electroplaques had a normal resting potential and were depolarized by acetylcholine and carbamylcholine similarly to normal cells. Other properties related to electrical inexcitability were also demonstrated. A pharmacological finding of considerable theoretical significance is that desensitization occurred on depolarizing cells with acetylcholine but was absent on depolarizing them with carbamylcholine.
Full Text
The Full Text of this article is available as a PDF (1.3 MB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- ALTAMIRANO M., COATES C. W., GRUNDFEST H. Mechanisms of direct and neural excitability in electroplaques of electric eel. J Gen Physiol. 1955 Jan 20;38(3):319–360. doi: 10.1085/jgp.38.3.319. [DOI] [PMC free article] [PubMed] [Google Scholar]
- ALTAMIRANO M., COATES C. W., GRUNDFEST H., NACHMANSOHN D. Electrical activity in electric tissue. III. Modifications of electrical activity by acetylcholine and related compounds. Biochim Biophys Acta. 1955 Apr;16(4):449–463. doi: 10.1016/0006-3002(55)90263-8. [DOI] [PubMed] [Google Scholar]
- AUGUSTINSSON K. B., JOHNELS A. G. The acetylcholine system of the electric organ of Malapterurus electricus. J Physiol. 1958 Mar 11;140(3):498–500. [PMC free article] [PubMed] [Google Scholar]
- AXELSSON J., THESLEFF S. A study of supersensitivity in denervated mammalian skeletal muscle. J Physiol. 1959 Jun 23;147(1):178–193. doi: 10.1113/jphysiol.1959.sp006233. [DOI] [PMC free article] [PubMed] [Google Scholar]
- BENNETT M. V., CRAIN S. M., GRUNDFEST H. Electrophysiology of supramedullary neurons in Spheroides maculatus. I. Orthodromic and antidromic responses. J Gen Physiol. 1959 Sep;43:159–188. doi: 10.1085/jgp.43.1.159. [DOI] [PMC free article] [PubMed] [Google Scholar]
- BROCK L. G., ECCLES R. M. The membrane potentials during rest and activity of the ray electroplate. J Physiol. 1958 Jul 14;142(2):251–274. doi: 10.1113/jphysiol.1958.sp006014. [DOI] [PMC free article] [PubMed] [Google Scholar]
- BURKE W., GINSBORG B. L. The electrical properties of the slow muscle fibre membrane. J Physiol. 1956 Jun 28;132(3):586–598. doi: 10.1113/jphysiol.1956.sp005551. [DOI] [PMC free article] [PubMed] [Google Scholar]
- DEL CASTILLO J., KATZ B. Biophysical aspects of neuro-muscular transmission. Prog Biophys Biophys Chem. 1956;6:121–170. [PubMed] [Google Scholar]
- GRUNDFEST H. An electrophysiological basis for neuropharmacology. Fed Proc. 1958 Dec;17(4):1006–1018. [PubMed] [Google Scholar]
- GRUNDFEST H. Electrical inexcitability of synapses and some consequences in the central nervous system. Physiol Rev. 1957 Jul;37(3):337–361. doi: 10.1152/physrev.1957.37.3.337. [DOI] [PubMed] [Google Scholar]
- GRUNDFEST H. General problems of drugs actions on bioelectric phenomena. Ann N Y Acad Sci. 1957 Mar 14;66(3):537–591. doi: 10.1111/j.1749-6632.1957.tb40748.x. [DOI] [PubMed] [Google Scholar]
- KATZ B., THESLEFF S. A study of the desensitization produced by acetylcholine at the motor end-plate. J Physiol. 1957 Aug 29;138(1):63–80. doi: 10.1113/jphysiol.1957.sp005838. [DOI] [PMC free article] [PubMed] [Google Scholar]