Abstract
Voltage clamped single nerve fibres of the frogPanta esculenta were treated with the amino groups specific reagents ethyl acetimidate and isethionyl acetimidate. Ethyl acetimidate is lipid soluble, relatively non-polar and can penetrate a membrane. Isethionyl acetimidate is lipid-insoluble, polar and membrane-impermeant. Treatment with ethyl acetimidate caused an irreversible reduction of Na currents and a shift of the voltage dependence of the steady-state sodium inactivation,h ∞ (E), in the hyperpolarizing direction. The voltage dependence of sodium activation was much less affected and a small shift into the depolarizing direction was observed. By contrast, the non-permeant reagent did not reduce the sodium currents and the shifts of theh ∞ (E) curve were smaller than the shifts caused by ethyl acetimidate. Furthermore, a small shift of the voltagedependence of activation in the hyperpolarizing direction was observed. As the modification procedure with imidoesters does not cause a change of net charge, the results cannot be explained by an effect of surface charge modification, rather, they seem to be due to a direct effect of amino group modification on the voltage dependence of inactivation.
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Abbreviations
- TNBS:
-
Trinitrobenzenesulfonic acid
- IAI:
-
isethionyl acetimidate
- EAI:
-
ethyl acetimidate
- MOPS:
-
morpholinopropanesulfonic acid
- TEA:
-
tetraethylammonium
- CHES:
-
(2-cyclohexylamino)-ethanesulfonic acid
References
Anderson GW, Zimmerman JE, Callahan FM (1964) The use of esters of N-hydroxysuccinimide in peptide synthesis. J Am Chem Soc 86:1839–1842
Brodwick MS, Eaton DC (1982) Chemical modification of excitable membranes. Proteins in the nervous system: Structure and function. Alan R. Liss, New York, pp 51–72
Cahalan MD, Pappone PA (1981) Chemical modification of sodium channel surface charges in frog skeletal muscle by trinitrobenzene sulphonic acid. J Physiol 321:127–139
Courtney KR (1975) Mechanism of frequency-dependent inhibition of sodium currents in frog myelinated nerve by the lidocaine derivative GEA 968. J Pharmacol Exp Ther 195:225–236
Courtney KR (1979) Extracellular pH selectively modulates recovery from sodium inactivation in frog myelinated nerve. Biophys J 28:363–368
Drouin H, Neumcke B (1974) Specific and unspecific charges at the sodium channels of the nerve membrane. Pflügers Arch Eur J Physiol 351:207–229
Frankenhaeuser B (1960) Quantitative description of sodium currents in myelinated nerve fibres of Xenopus laevis. J Physiol 151:491–501
Hodgkin AL, Huxley AF (1952) A quantitative description of membrane current and its application to conduction and excitation in nerve. J Physiol 117:500–544
Hunter MJ, Ludwig ML (1962) The reaction of imidoesters with proteins and related small molecules. J Am Chem Soc 84:3491–3504
Nonner W (1969) A new voltage clamp method for Ranvier nodes. Pflügers Arch Eur J Physiol 309:176–192
Okuyama T, Satake K (1960) On the preparation and properties of 2,4,6-trinitrophenyl-amino acids and-peptides. J Biochem 47:454–466
Rack M, Hu S, Rubly N, Waschow C (1984) Effects of chemical modification of amino and sulfhydryl groups on the voltageclamped frog node of Ranvier. Pflügers Arch Eur J Physiol 400:403–408
Rack M (1984) Amino group modification without destruction of charge affects sodium currents in frog nerve. Pflügers Arch Eur J Physiol 402:R36
Stämpfli R (1969) Dissection of single nerve fibres and measurements of membrane potential changes of Ranvier nodes by means of the double air gap method. In: Passow H, Stämpfli R (eds) Laboratory techniques in membrane biophysics. Springer, Berlin Heidelberg New York, pp 157–166
Stämpfli R, Hille B (1976) Electrophysiology of the peripheral myelinated nerve. In: Llinás R, Precht W (eds) Frog neurobiology. Springer, Berlin Heidelberg New York, pp 3–32
Strichartz GR (1973) The inhibition of sodium currents in myelinated nerve by quaternary derivatives of lidocaine. J Gen Physiol 62:37–57
Whiteley NM, Berg HC (1974) Amidination of the outer and inner surfaces of the human erythrocyte membrane. J Mol Biol 87:541–561
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Rack, M. Effects of chemical modification of amino groups by two different imidoesters on voltage-clamped nerve fibres of the frog. Pflugers Arch. 404, 126–130 (1985). https://doi.org/10.1007/BF00585407
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DOI: https://doi.org/10.1007/BF00585407