Abstract
The double-microelectrode voltage clamp technique was applied to small spheroidal aggregates of heart cells from 7-d chick embryos. A third intracellular electrode was sometimes used to monitor spatial homogeneity. On average, aggregates were found to deviate from isopotentiality by 12% during the first 3--5 ms of large depolarizing voltage steps, when inward current was maximal, and by less than 3% thereafter. Two components of inward current were recorded: (a) a fast, transient current associated with the rapid upstroke of the action potential, which was abolished by tetrodotoxin (TTX); and (b) a slower inward current related to the plateau, which was not affected by TTX but was blocked by D600. The magnitudes, kinetics, and voltage dependence of these two inward currents and a delayed outward current were similar to those reported for adult cardiac preparations. From a holding potential of -60 mV, the peak fast component at the point of maximal activation (-20 mV) was -185 microA/cm2. This value was about seven times greater than the maximal slow component which peaked at 0 mV. The ratio of rate constants for the decay of the two currents was between 10:1 and 30:1.
Full Text
The Full Text of this article is available as a PDF (1.4 MB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Attwell D., Cohen I. The voltage clamp of multicellular preparations. Prog Biophys Mol Biol. 1977;31(3):201–245. doi: 10.1016/0079-6107(78)90009-3. [DOI] [PubMed] [Google Scholar]
- Beeler G. W., Jr, Reuter H. Membrane calcium current in ventricular myocardial fibres. J Physiol. 1970 Mar;207(1):191–209. doi: 10.1113/jphysiol.1970.sp009056. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Beeler G. W., Jr, Reuter H. Voltage clamp experiments on ventricular myocarial fibres. J Physiol. 1970 Mar;207(1):165–190. doi: 10.1113/jphysiol.1970.sp009055. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Beeler G. W., Reuter H. Reconstruction of the action potential of ventricular myocardial fibres. J Physiol. 1977 Jun;268(1):177–210. doi: 10.1113/jphysiol.1977.sp011853. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Besseau A., Gargouïl Y. M. Ionic currents in rat ventricular heart fibres: voltage-clamp experiments using double sucrose-gap technique. J Physiol. 1969 Oct;204(2):95P–96P. [PubMed] [Google Scholar]
- Bezanilla F., Rojas E., Taylor R. E. Sodium and potassium conductance changes during a membrane action potential. J Physiol. 1970 Dec;211(3):729–751. doi: 10.1113/jphysiol.1970.sp009301. [DOI] [PMC free article] [PubMed] [Google Scholar]
- COLE K. S., MOORE J. W. Ionic current measurements in the squid giant axon membrane. J Gen Physiol. 1960 Sep;44:123–167. doi: 10.1085/jgp.44.1.123. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Chesnais J. M., Coraboeuf E., Sauviat M. P., Vassas J. M. Sensitivity to H, Li and Mg ions of the slow inward sodium current in frog atrial fibres. J Mol Cell Cardiol. 1975 Sep;7(9):627–642. doi: 10.1016/0022-2828(75)90140-6. [DOI] [PubMed] [Google Scholar]
- Connor J., Barr L., Jakobsson E. Electrical characteristics of frog atrial trabeculae in the double sucrose gap. Biophys J. 1975 Oct;15(10):1047–1067. doi: 10.1016/S0006-3495(75)85882-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
- DECK K. A., KERN R., TRAUTWEIN W. VOLTAGE CLAMP TECHNIQUE IN MAMMALIAN CARDIAC FIBRES. Pflugers Arch Gesamte Physiol Menschen Tiere. 1964 Jun 9;280:50–62. doi: 10.1007/BF00412615. [DOI] [PubMed] [Google Scholar]
- DRAPER M. H., WEIDMANN S. Cardiac resting and action potentials recorded with an intracellular electrode. J Physiol. 1951 Sep;115(1):74–94. doi: 10.1113/jphysiol.1951.sp004653. [DOI] [PMC free article] [PubMed] [Google Scholar]
- DeHaan R. L. The potassium-sensitivity of isolated embryonic heart cells increases with development. Dev Biol. 1970 Oct;23(2):226–240. doi: 10.1016/0012-1606(70)90096-5. [DOI] [PubMed] [Google Scholar]
- DeHann R. L. Regulation of spontaneous activity and growth of embryonic chick heart cells in tissue culture. Dev Biol. 1967 Sep;16(3):216–249. doi: 10.1016/0012-1606(67)90025-5. [DOI] [PubMed] [Google Scholar]
- Dehaan R. L., Fozzard H. A. Membrane response to current pulses in spheroidal aggregates of embryonic heart cells. J Gen Physiol. 1975 Feb;65(2):207–222. doi: 10.1085/jgp.65.2.207. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Dudel J., Rüdel R. Voltage and time dependence of excitatory sodium current in cooled sheep Purkinje fibres. Pflugers Arch. 1970;315(2):136–158. doi: 10.1007/BF00586657. [DOI] [PubMed] [Google Scholar]
- Elsas L. J., Wheeler F. B., Danner D. J., DeHaan R. L. Amino acid transport by aggregates of cultured chicken heart cells. Effect of insulin. J Biol Chem. 1975 Dec 25;250(24):9381–9390. [PubMed] [Google Scholar]
- Fozzard H. A., Beeler G. W., Jr The voltage clamp and cardiac electrophysiology. Circ Res. 1975 Oct;37(4):403–413. doi: 10.1161/01.res.37.4.403. [DOI] [PubMed] [Google Scholar]
- Goldman Y., Morad M. Measurement of transmembrane potential and current in cardiac muscle: a new voltage clamp method. J Physiol. 1977 Jul;268(3):613–654. doi: 10.1113/jphysiol.1977.sp011875. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Haas H. G., Kern R., Einwächter H. M., Tarr M. Kinetics of Na inactivation in frog atria. Pflugers Arch. 1971;323(2):141–157. doi: 10.1007/BF00586445. [DOI] [PubMed] [Google Scholar]
- Hellam D. C., Studt J. W. A core-conductor model of the cardiac Purkinje fibre based on structural analysis. J Physiol. 1974 Dec;243(3):637–660. doi: 10.1113/jphysiol.1974.sp010770. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Johnson E. A., Lieberman M. Heart: excitation and contraction. Annu Rev Physiol. 1971;33:479–532. doi: 10.1146/annurev.ph.33.030171.002403. [DOI] [PubMed] [Google Scholar]
- Kass R. S., Tsien R. W. Multiple effects of calcium antagonists on plateau currents in cardiac Purkinje fibers. J Gen Physiol. 1975 Aug;66(2):169–192. doi: 10.1085/jgp.66.2.169. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kensler R. W., Brink P., Dewey M. M. Nexus of frog ventricle. J Cell Biol. 1977 Jun;73(3):768–781. doi: 10.1083/jcb.73.3.768. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kohlhardt M., Bauer B., Krause H., Fleckenstein A. Differentiation of the transmembrane Na and Ca channels in mammalian cardiac fibres by the use of specific inhibitors. Pflugers Arch. 1972;335(4):309–322. doi: 10.1007/BF00586221. [DOI] [PubMed] [Google Scholar]
- McAllister R. E., Noble D., Tsien R. W. Reconstruction of the electrical activity of cardiac Purkinje fibres. J Physiol. 1975 Sep;251(1):1–59. doi: 10.1113/jphysiol.1975.sp011080. [DOI] [PMC free article] [PubMed] [Google Scholar]
- McDonald T. F., DeHaan R. L. Ion levels and membrane potential in chick heart tissue and cultured cells. J Gen Physiol. 1973 Jan;61(1):89–109. doi: 10.1085/jgp.61.1.89. [DOI] [PMC free article] [PubMed] [Google Scholar]
- McDonald T. F., Sachs H. G., DeHaan R. L. Development of sensitivity to tetrodotoxin in beating chick embryo hearts, single cells, and aggregates. Science. 1972 Jun 16;176(4040):1248–1250. doi: 10.1126/science.176.4040.1248. [DOI] [PubMed] [Google Scholar]
- McDonald T. F., Sachs H. G. Electrical activity in embryonic heart cell aggregates. Developmental aspects. Pflugers Arch. 1975;354(2):151–164. doi: 10.1007/BF00579945. [DOI] [PubMed] [Google Scholar]
- McGuigan J. A. Some limitations of the double sucrose gap, and its use in a study of the slow outward current in mammalian ventricular muscle. J Physiol. 1974 Aug;240(3):775–806. doi: 10.1113/jphysiol.1974.sp010634. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Moolenaar W. H., Spector I. Ionic currents in cultured mouse neuroblastoma cells under voltage-clamp conditions. J Physiol. 1978 May;278:265–286. doi: 10.1113/jphysiol.1978.sp012303. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Narahashi T. Chemicals as tools in the study of excitable membranes. Physiol Rev. 1974 Oct;54(4):813–889. doi: 10.1152/physrev.1974.54.4.813. [DOI] [PubMed] [Google Scholar]
- Nathan R. D., DeHaan R. L. In vitro differentiation of a fast Na+ conductance in embryonic heart cell aggregates. Proc Natl Acad Sci U S A. 1978 Jun;75(6):2776–2780. doi: 10.1073/pnas.75.6.2776. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Nathan R. D., Pooler J. P., DeHaan R. L. Ultraviolet-induced alterations of beat rate and electrical properties of embryonic chick heart cell aggregates. J Gen Physiol. 1976 Jan;67(1):27–44. doi: 10.1085/jgp.67.1.27. [DOI] [PMC free article] [PubMed] [Google Scholar]
- New W., Trautwein W. Inward membrane currents in mammalian myocardium. Pflugers Arch. 1972;334(1):1–23. doi: 10.1007/BF00585997. [DOI] [PubMed] [Google Scholar]
- Noma A., Irisawa H. Membrane currents in the rabbit sinoatrial node cell as studied by the double microelectrode method. Pflugers Arch. 1976 Jun 29;364(1):45–52. doi: 10.1007/BF01062910. [DOI] [PubMed] [Google Scholar]
- Ramón F., Anderson N., Joyner R. W., Moore J. W. Axon voltage-clamp simulations. A multicellular preparation. Biophys J. 1975 Jan;15(1):55–69. doi: 10.1016/S0006-3495(75)85791-2. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Reuter H. Divalent cations as charge carriers in excitable membranes. Prog Biophys Mol Biol. 1973;26:1–43. doi: 10.1016/0079-6107(73)90016-3. [DOI] [PubMed] [Google Scholar]
- Rose B., Simpson I., Loewenstein W. R. Calcium ion produces graded changes in permeability of membrane channels in cell junction. Nature. 1977 Jun 16;267(5612):625–627. doi: 10.1038/267625a0. [DOI] [PubMed] [Google Scholar]
- Rougier O., Vassort G., Garnier D., Gargouil Y. M., Coraboeuf E. Existence and role of a slow inward current during the frog atrial action potential. Pflugers Arch. 1969;308(2):91–110. doi: 10.1007/BF00587018. [DOI] [PubMed] [Google Scholar]
- Sachs H. G., DeHaan R. L. Embryonic myocardial cell aggregates: volume and pulsation rate. Dev Biol. 1973 Jan;30(1):233–240. doi: 10.1016/0012-1606(73)90064-x. [DOI] [PubMed] [Google Scholar]
- Sachs H. G., McDonald T. F., Springer M. Cytochalasin B and embryonic heart muscle: contractility, excitability and ultrastructure. J Cell Sci. 1974 Jan;14(1):163–185. doi: 10.1242/jcs.14.1.163. [DOI] [PubMed] [Google Scholar]
- Shigenobu K., Schneider J. A., Sperelakis N. Verapamil blockade of slow Na+ and Ca++ responses in myocardial cells. J Pharmacol Exp Ther. 1974 Aug;190(2):280–288. [PubMed] [Google Scholar]
- Shigenobu K., Sperelakis N. Development of sensitivity to tetrodotoxin of chick embryonic hearts with age. J Mol Cell Cardiol. 1971 Dec;3(3):271–286. doi: 10.1016/0022-2828(71)90046-0. [DOI] [PubMed] [Google Scholar]
- Tarr M., Trank J. W. An assessment of the double sucrose-gap voltage clamp technique as applied to frog atrial muscle. Biophys J. 1974 Sep;14(9):627–643. doi: 10.1016/S0006-3495(74)85940-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Trautwein W., McDonald T. F. Membrane conductance measurements in cat ventricular muscle. J Mol Cell Cardiol. 1978 Apr;10(4):387–394. doi: 10.1016/0022-2828(78)90385-1. [DOI] [PubMed] [Google Scholar]
- Trautwein W., McDonald T. F., Tripathi O. Calcium conductance and tension in mammalian ventricular muscle. Pflugers Arch. 1975;354(1):55–74. doi: 10.1007/BF00584503. [DOI] [PubMed] [Google Scholar]
- de Hemptinne A. Voltage clamp analysis in isolated cardiac fibres as performed with two different perfusion chambres for double sucrose gap. Pflugers Arch. 1976 May 6;363(1):87–95. doi: 10.1007/BF00587407. [DOI] [PubMed] [Google Scholar]