Skip to main content
SpringerLink
Log in

Sodium action potentials induced by calcium chelation in rat uterine smooth muscle

  • Excitable Tissues and Central Nervous Physiology
  • Published:
Pflügers Archiv Aims and scope Submit manuscript

Abstract

Muscular strips of rat myometrium were exposed to Ca-free solutions in the presence of low concentrations of EGTA (0.1–1 mM). A study of electrical activity was carried out using intracellular recording techniques and the double sucrose-gap apparatus. The results were as followed:

  1. (1)

    After 5–15 min the resting membrane potential was depolarized to about −35 mV und a rhythmic activity appeared. The potentials had no overshoot and their duration was noticeably prolonged showing a sustained plateau close to zero potential. Rhythmic activity was observed in a definite membrane potential range. The effects were essentially reversed upon Ca-replacement.

  2. (2)

    The maximal amplitude of the potentials was strongly dependent on the external Na-concentration. At low Na-concentrations (13 mM), the membrane repolarized to its normal resting value (about −50 mV).

  3. (3)

    The potentials were unaffected by tetrodotoxin (2μM). They were inhibited by Mn (0.1 mM) and D600 (0.1–1 μM) and by increasing Mg concentration (1.24 mM) or Ca concentration (10−3 mM) after 1 h in the presence of EGTA. Higher concentrations of Mn (1–2.5 mM) also repolarized the membrane to its normal resting potential. Tetraethylammonium ions (20 mM) increased both amplitude and duration of the responses but did not blocked the repolarization.

  4. (4)

    Inward Na currents characterized by a slow inactivation were recorded on voltage-clamped preparations.

  5. (5)

    Inhibition of Na-pumping with K-free solution or ouabain (0.1–1 mM) blocked the rhythmic activity and maintained the membrane potential at a steady-state depolarized value. Action potentials reappeared by application of inward current pulses which repolarized the membrane to about −45 mV.

These results suggest that Ca-chelation induces membrane permeability changes resulting essentially in: 1) an increase in resting Na-conductance, 2) a prolonged Na-inward current entering through channels normally used by Ca ions, and 3) a reduction in K-conductance. However, active Na pumping does indeed participate to the generation of rhythmic activity.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

References

  • Anderson NC, Ramon F, Snyder A (1971) Studies on calcium and sodium in uterine smooth muscle excitation under current-clamp and voltage-clamp conditions. J Gen Physiol 58:322–339

    Google Scholar 

  • Ashcroft FM, Stanfield PR (1980) Inactivation of calcium currents in skeletal muscle fibres of an insect depends on calcium entry. J Physiol (Lond) 308:36P

    Google Scholar 

  • Bolton TB, Tomita T, Vassort G (1981) Voltage clamp and the measurement of ionic conductances in smooth muscle. In: Bülbring E, Brading AF, Jones AW, Tomita T (eds) Smooth muscle: an assessment of current knowledge. Ed. Arnold, London, pp 47–63

    Google Scholar 

  • Brown AM, Morimoto K, Tsuda Y, Wilson DL (1981) Calcium current-dependent and voltage-dependent inactivation of calcium channels inHelix aspersa. J Physiol (Lond) 320:193–218

    Google Scholar 

  • Brading AF, Sneddon P (1980) Evidence for multiple sources of calcium for activation of the contractile mechanism of guinea-pig taenia coli on stimulation with carbachol. Br J Pharmacol 70:229–240

    Google Scholar 

  • Bülbring E, Tomita T (1970) Effects of Ca removal on the smooth muscle of the guinea-pig taenia coli. J Physiol (Lond) 210:217–232

    Google Scholar 

  • Casteels R, Raeymakers L (1979) The action of acetylcholine and catecholamines on an intracellular calcium store in the smooth muscle cells of the guinea-pig taenia coli. J Physiol (Lond) 294:51–68

    Google Scholar 

  • Fleckenstein A (1977) Specific pharmacology of calcium in myocardium, cardiac pacemakers, and vascular smooth muscle. Ann Rev Pharmacol Toxicol 17:149–166

    Google Scholar 

  • Fleckenstein A, Grün G, Tritthart H, Byon YK (1971) Uterus-Relaxation durch hochaktive Ca2+-antagonistische Hemmstoffe der elektromechanischen Koppelung wie Isotopin (Verapamil, Iproveratril), Substanz D600 und Segontin (Prenylamin). Klin Wochenschr 49:32–41

    Google Scholar 

  • Garnier D, Rougier O, Gargouil YM, Coraboeuf E (1969) Analyse électro-physiologique du plateau des réponses myocardiques, mise en évidence d'un courant lent entrant en absence d'ions bivalents. Pflügers Arch 313:321–342

    Google Scholar 

  • Goto M, Abe Y (1964) Effects of EDTA on the membrane potential and tension of ventricular muscle of the rabbit. Jpn J Physiol 14:135–146

    Google Scholar 

  • Grosset G, Mironneau J (1977) An analysis of the actions of prostaglandin E1 on membrane currents and contraction in uterine smooth muscle. J Physiol (Lond) 270:765–784

    Google Scholar 

  • Hagiwara S, Nakajima S (1966) Differences in Na+ and Ca2+ spikes as examined by application of tetrodotoxin, procaine and manganese ions. J Gen Physiol 49:793–805

    Google Scholar 

  • Hille B (1967) The selective inhibition of delayed potassium currents in nerve by tetraethylammonium ion. J Gen Physiol 50:1287–1302

    Google Scholar 

  • Hoffmann BF, Suckling EE (1956) Effect of several cations on transmembrane potentials of cardiac muscle. Am J Physiol 186:317–324

    Google Scholar 

  • Kao CY (1966) Tetrodotoxin, saxitoxin and their significance in the study of excitation phenomena. Pharmacol Rev 18:977–1049

    Google Scholar 

  • Kao CY, Mc Cullough JR (1975) Ionic currents in the uterine smooth muscle. J Physiol (Lond) 246:1–36

    Google Scholar 

  • Keatinge WR (1968) Ionic requirements for arterial action potential. J Physiol (Lond) 194:169–182

    Google Scholar 

  • Kuriyama H, Suzuki H (1976) Changes in electrical properties of rat myometrium during gestation and following hormonal treatments. J Physiol (Lond) 260:315–332

    Google Scholar 

  • Mangel A, Van Breemen C (1981) Rhythmic electrical activity in rabbit aorta induced by EGTA. J Exp Biol 90:339–342

    Google Scholar 

  • Marshall JM, Kroeger EA (1973) Adrenergic influences on uterine smooth muscle. Phil Trans R Soc Lond B 265:135–148

    Google Scholar 

  • Miller DJ (1979) Are cardiac cells “skinned” by EGTA or EDTA. Nature 277:142–143

    Google Scholar 

  • Mironneau J (1973) Excitation-contraction coupling in voltage clamped uterine smooth muscle. J Physiol (Lond) 233:127–141

    Google Scholar 

  • Mironneau J (1974) Voltage clamp analysis of the ionic currents in uterine smooth muscle using the double sucrose gap method. Pflügers Arch 352:197–210

    Google Scholar 

  • Mironneau J, Savineau JP (1980) Effects of calcium ions on outward membrane currents in rat uterine smooth muscle. J Physiol. (Lond) 302:411–425

    Google Scholar 

  • Plant TD, Standen NB (1981) Calcium current inactivation in identified neurones ofHelix aspersa. J Physiol (Lond) 321:273–285

    Google Scholar 

  • Prosser CL, Kreulen DL, Weigel RJ, Yau W (1977) Prolonged action potentials in gastrointestinal muscles induced by calcium chelation. Am J Physiol 233:C19–C24

    Google Scholar 

  • Reiner O, Marshall JM (1975) Action of D600 on spontaneous and electrically stimulated activity of the parturient rat uterus. Naunyn-Schmiedeberg's Arch Pharmacol 290:21–28

    Google Scholar 

  • Standen NB (1981) Ca channel inactivation by intracellular Ca injection intoHelix neurones. Nature 293:158–159

    Google Scholar 

  • Tomita T (1981) Electrical activity (spikes and slow waves) in gastrointestinal smooth muscles. In: Bülbring E, Brading AF, Jones AW, Tomita T (eds) Smooth muscle: an assessment of current knowledge. Ed. Arnold, London, pp 127–156

    Google Scholar 

  • Taylor GS, Paton DM, Daniel EE (1970) Characteristics of electrogenic sodium pumping in rat myometrium. J Gen Physiol 56:360–375

    Google Scholar 

  • Thompson SH (1977) Three pharmacologically distinct potassium channels in molluscan neurones. J Physiol (Lond) 265:465–488

    Google Scholar 

  • Tritthart H, Mc Leod DP, Stierle HE, Krause H (1973) Effects of Ca-free and EDTA-containing Tyrode solution on transmembrane electrical activity and contraction in guinea-pig papillary muscle. Pflügers Arch 338:361–376

    Google Scholar 

  • Vassort G (1975) Voltage-clamp analysis of transmembrane ionic currents in guinea-pig myometrium: evidence for an initial potassium activation triggered by calcium influx. J Physiol (Lond) 252:713–734

    Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Laboratoire de Physiologie Cellulaire, Institut de Biochimie Cellulaire et Neurochimie du CNRS Université de Bordeaux II, 1 rue Camille Saint-Saëns, F-33077, Bordeaux Cedex, France

    Jean Mironneau, Daniel Eugene & Chantal Mironneau

Authors
  1. Jean Mironneau
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Daniel Eugene
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Chantal Mironneau
    View author publications

    You can also search for this author in PubMed Google Scholar

Rights and permissions

Reprints and permissions

About this article

Cite this article

Mironneau, J., Eugene, D. & Mironneau, C. Sodium action potentials induced by calcium chelation in rat uterine smooth muscle. Pflugers Arch. 395, 232–238 (1982). https://doi.org/10.1007/BF00584815

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1007/BF00584815

Key words

Search

Navigation