Pflügers Archiv

, Volume 404, Issue 2, pp 190–196 | Cite as

Sodium current in single myocardial mouse cells

  • Klaus Benndorf
  • Wolfgang Boldt
  • Bernd Nilius
Excitable Tissues and Central Nervous Physiology

Abstract

Morphologically intact single myocardial cells of the adult mouse show a length of 132±20 μm, a width of 21±5 μ, and a height of 10±4 μm (all mean ± SD) and are brick-like in shape. A one suction pipette method is used for voltage clamp of those single cells. The determined time constant of capacitive current τ=35±14 μs is very short. Series resistancers, membrane resistancerm, and membrane capacitycm are calculated to be 192±48 kΩ, 6.1±1.1 MΩ, and 186±92 pF (all mean ± SD), respectively. Assuming the specific unit membrane capacitance of 1 μF/cm2, a total membrane area of 1.86×10−4 cm2 is determined yielding a specific membrane resistanceRm of 1,134 Ωcm2. Settling time of voltage clamp is 30 μs. TTX-block of sodium current is described by 1:1 binding with aKD value of 1.4×10−6M. Using a reduced extracellular sodium concentration the maximum Na current is between 25 and 40 nA at voltages between −40 and −30 mV. Currents of between +20 and +30 mV reverse in an outward direction. Inward currents are approximated by a m3h model. The time constant of activation decreases from 0.7 ms at −60 mV to 0.12 ms at +20 mV. The time constant of inactivation falls from 9.1 ms at −60 mV to 0.6 ms at +20 mV.

Steady state inactivationh is characterized by the half maximum valueVH=−76.1±4.3 mV and the slope parameters=−6.3±1.1 mV (mean ± SD). A prepulse duration of 500 ms is essential for real steady state inactivation. Steady state activationm and inactivationh overlap each other defining a maximum window current at −65 mV.

Key words

Single myocardial mouse cells Sodium current Current voltage relation m h 

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References

  1. Bean BP (1981) Sodium channel inactivation in the crayfish giant axon-must channels open before inactivating? Biophys J 35:595–614Google Scholar
  2. Beeler GW, Reuter H (1976) Voltage clamp experiments on ventricular myocardial fibres. J Physiol (Lond) 207:165–190Google Scholar
  3. Bodewei R, Hering S, Lemke B, Rosenstraukh LV, Undrovinas A, Wollenberger A (1982) Characterization of the fast sodium current in isolated rat myocardial cells: simulation of the clamped membrane potential. J Physiol (Lond) 325:301–315Google Scholar
  4. Brown AM, Lee KS, Powell T (1981a) Voltage clamp and internal perfusion of single rat heart muscle cells. J Physiol (Lond) 318:455–477Google Scholar
  5. Brown AM, Lee KS, Powell T (1981b) Sodium current in single rat heart muscle cells. J Physiol (Lond) 318:479–500Google Scholar
  6. Brown KM, Dennis JE Jr (1972) Derivative free analogues of the Levenberg-Marquard and Gauss algorithms for nonlinear least squares approximation. Numer Math 18:289–297Google Scholar
  7. Bustamate JO, McDonald TF (1983) Sodium currents in segments of human heart cells. Science 220:320–321Google Scholar
  8. Cachelin AB, De Peyer JE, Kokubun S, Reuter H (1983) Sodium channels in cultured cardiac cells. J Physiol (Lond) 340:389–401Google Scholar
  9. Cohen CJ, Bean BP, Colatsky TJ, Tsien RW (1981) Tetrodotoxin block of sodium channels in rabbit Purkinje fibers. J Gen Physiol 78:383–411Google Scholar
  10. Colatsky TJ (1980) Voltage clamp measurements of sodium channel properties in rabbit cardiac Purkinje fibers. J Physiol (Lond) 305:215–235Google Scholar
  11. Dudel J, Peper K, Rüdel R, Trautwein W (1967) The effect of tetrodotoxin on the membrane current in cardiac muscle (Purkinje fibers). Pflügers Arch 295:213–226Google Scholar
  12. Dudel J, Rüdel R (1970) Voltage and time dependence of excitory sodium current in cooled sheep Purkinje fibers. Pflügers Arch 315:136–158Google Scholar
  13. Hodgkin AL, Huxley AF (1952) The dual effect of membrane potential on sodium conductance in the giant axon of Loligo. J Physiol (Lond) 116:497–506Google Scholar
  14. Hume JR, Giles W (1983) Ionic currents in single isolated bullfrog atrial cells. J Gen Physiol 81:153–194Google Scholar
  15. Irisawa H, Kokubun S (1983) Modulation by intracellular ATP and cyclic AMP of the slow inward current in isolated single ventricular cells of the guinea pig. J Physiol (Lond) 338:321–337Google Scholar
  16. Isenberg G, Klöckner U (1980) Glycocalyx is not required for slow inward current in isolated rat heart myocytes. Nature 284:358–360Google Scholar
  17. Isenberg G, Klöckner U (1982a) Calcium tolerant ventricular myocytes prepared by preincubation in a “KB medium”. Pflügers Arch 395:6–18Google Scholar
  18. Isenberg G, Klöckner U (1982b) Calcium currents of isolated bovine ventricular myocytes are fast and of large amplitude. Pflügers Arch 395:30–41Google Scholar
  19. Johnson EA, Lieberman M (1971) Heart: excitation and contraction. Ann Rev Physiol 33:479–529Google Scholar
  20. Kostyuk PG, Krishtal OA, Pidoplichko VI (1975) Effect of internal fluoride and phosphate on membrane currents during intracellular dialysis of nerve cells. Nature 257:691–693Google Scholar
  21. Lee KS, Akaike N, Brown AM (1978) Properties of internally perfused voltage-clamped isolated nerve cell bodies. J Gen Physiol 71:489–507Google Scholar
  22. Lee KS, Tsien RW (1982) Reversal of current through calcium channels in dialysed single heart cells. Nature 297:498–501Google Scholar
  23. Lee KS, Tsien RW (1983) Mechanism of calcium channel blockade by verapamil, D 600, diltiazem and nitrendipine in single dialysed heart cells. Nature 302:790–794Google Scholar
  24. Lee KS, Weeks TA, Kao RL, Akaike N, Brown AM (1979) Sodium current in single heart muscle cells. Nature 278:269–271Google Scholar
  25. Nakamura Y, Nakajama S, Grundfest H (1965) The action of tetrodotoxin on electrogenic components of squid giant axons. J Gen Physiol 48:985–996Google Scholar
  26. Rajs J, Sundberg M, Sundby GB, Danell N, Tornling G, Biberfeld P, Jakobson SW (1978) A rapid method for the isolation of viable cardiac myocytes from adult rat. Exp Cell Res 115:183–189Google Scholar
  27. Taniguchi J, Kokubun S, Noma A, Irisawa H (1981) Spontaneously active cells isolated from the sino-atrial and atrioventricular nodes of the rabbit heart. Jap J Physiol 31:547–558Google Scholar
  28. Undrovinas AI, Yushmanova AV, Hering S, Rosenstraukh LV (1980) Voltage clamp method on single cardiac cells from adult rat heart. Experientia 36:572–573Google Scholar
  29. Weidmann S (1955) Effects of calcium ions and local anaesthetics on electrical properties of Purkinje fibres. J Physiol (Lond) 129:568–582Google Scholar

Copyright information

© Springer-Verlag 1985

Authors and Affiliations

  • Klaus Benndorf
    • 1
  • Wolfgang Boldt
    • 1
  • Bernd Nilius
    • 1
  1. 1.Julius Bernstein Institute for PhysiologyMartin Luther University Halle WittenbergHalle (Saale)German Democratic Republic

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