Skip to main content
PMC home page
The Journal of General Physiology logoLink to The Journal of General Physiology
. 1982 Jun 1;79(6):1017–1039. doi: 10.1085/jgp.79.6.1017

Frequency-dependent excitability of "membrane" slow responses of Rabbit left atrial trabeculae in the presence of Ba2+ and high K+

PMCID: PMC2216457  PMID: 7108486

Abstract

Small trabeculae of rabbit left atrium immersed in TKBa solution (Tyrode with 10 mM K+ and 1 mM Ba2+) were used to study frequency dependence of "membrane" slow response excitability at long cycle lengths (greater than 1 s). In TKBa, stimuli generate graded, low- amplitude (2-15 mV) subliminal responses of variable long duration (up to 450 ms). A full all-or-none slow response is generated when a subliminal response depolarizes the membrane to about--35 mV. Subliminal response amplitude and rate of rise augment with stimulus intensity-duration product. For a fixed stimulus, the subliminal response is larger and faster at higher frequencies. Sudden changes in stimulus frequency or time course induce changes in subliminal response tha take four to eight cycles to attain steady state. For a fixed stimulus, slow response latency shortens progressively during the first few cycles after a sudden increase in frequency or when a rested preparation is excited (latency adaptation phenomenon, LAP). Slow response threshold stimulus requirements decrease during LAP (excitability hysteresis). The degree of excitability hysteresis is dependent on stimulation frequency and is more pronounced at higher frequencies. Frequency sensitivity of subliminal response (which causes frequency sensitivity of slow response excitability) is explained in terms of a transient state of enhancement set up by each stimulus. The enhanced state decays between stimuli with a half-time of approximately 4 s, thus allowing cumulative effects to become evident at rates above 0.1 Hz.

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.

  1. Antoni H., Oberdisse E. Elektrophysiologische Untersuchungen über die Barium-induzierte Schrittmacher-Aktivität im isolierten Säugetiermyokard. Pflugers Arch Gesamte Physiol Menschen Tiere. 1965 Jun 15;284(3):259–272. [PubMed] [Google Scholar]
  2. 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]
  3. Bonke F. I. Passive electrical properties of atrial fibers of the rabbit heart. Pflugers Arch. 1973 Mar 5;339(1):1–15. doi: 10.1007/BF00586977. [DOI] [PubMed] [Google Scholar]
  4. Connor J. A., Prosser C. L., Weems W. A. A study of pace-maker activity in intestinal smooth muscle. J Physiol. 1974 Aug;240(3):671–701. doi: 10.1113/jphysiol.1974.sp010629. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Connor J. A. Slow repetitive activity from fast conductance changes in neurons. Fed Proc. 1978 Jun;37(8):2139–2145. [PubMed] [Google Scholar]
  6. 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]
  7. De Mello W. C. Passive electrical properties of the atrio-ventricular node. Pflugers Arch. 1977 Oct 19;371(1-2):135–139. doi: 10.1007/BF00580781. [DOI] [PubMed] [Google Scholar]
  8. Ferrier G. R., Saunders J. H., Mendez C. A cellular mechanism for the generation of ventricular arrhythmias by acetylstrophanthidin. Circ Res. 1973 May;32(5):600–609. doi: 10.1161/01.res.32.5.600. [DOI] [PubMed] [Google Scholar]
  9. Gulrajani R. M., Roberge F. A. Possible mechanisms underlying bursting pacemaker discharges in invertebrate neurons. Fed Proc. 1978 Jun;37(8):2146–2152. [PubMed] [Google Scholar]
  10. Hagiwara S., Byerly L. Calcium channel. Annu Rev Neurosci. 1981;4:69–125. doi: 10.1146/annurev.ne.04.030181.000441. [DOI] [PubMed] [Google Scholar]
  11. Hagiwara S., Nakajima S. Effects of the intracellular Ca ion concentration upon the excitability of the muscle fiber membrane of a barnacle. J Gen Physiol. 1966 Mar;49(4):807–818. doi: 10.1085/jgp.49.4.807. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Hermsmeyer K., Sperelakis N. Decrease in K+ conductance and depolarization of frog cardiac muscle produced by Ba++. Am J Physiol. 1970 Oct;219(4):1108–1114. doi: 10.1152/ajplegacy.1970.219.4.1108. [DOI] [PubMed] [Google Scholar]
  13. Hiraoka M., Okamoto Y., Sano T. Effects of Ca+ and K+ on oscillatory afterpotentials in dog ventricular muscle fibers. J Mol Cell Cardiol. 1979 Oct;11(10):999–1015. doi: 10.1016/0022-2828(79)90391-2. [DOI] [PubMed] [Google Scholar]
  14. Kamiyama A., Matsuda K. Electrophysiological properties of the canine ventricular fiber. Jpn J Physiol. 1966 Aug 15;16(4):407–420. doi: 10.2170/jjphysiol.16.407. [DOI] [PubMed] [Google Scholar]
  15. Kass R. S., Lederer W. J., Tsien R. W., Weingart R. Role of calcium ions in transient inward currents and aftercontractions induced by strophanthidin in cardiac Purkinje fibres. J Physiol. 1978 Aug;281:187–208. doi: 10.1113/jphysiol.1978.sp012416. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Masuda M. O., de Carvalho A. P. Rate and rhythm dependency of propagation from normal myocardium to a Ba++, K+-induced slow response zone in rabbit left atrium. Circ Res. 1982 Mar;50(3):419–427. doi: 10.1161/01.res.50.3.419. [DOI] [PubMed] [Google Scholar]
  17. New W., Trautwein W. The ionic nature of slow inward current and its relation to contraction. Pflugers Arch. 1972;334(1):24–38. doi: 10.1007/BF00585998. [DOI] [PubMed] [Google Scholar]
  18. Niedergerke R., Orkand R. K. The dual effect of calcium on the action potential of the frog's heart. J Physiol. 1966 May;184(2):291–311. doi: 10.1113/jphysiol.1966.sp007916. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Paes de Carvalho A. P., Hoffman B. F., Langan W. B. Two components of the cardiac action potential. Nature. 1966 Aug 27;211(5052):938–940. doi: 10.1038/211938a0. [DOI] [PubMed] [Google Scholar]
  20. Pappano A. J. Calcium-dependent action potentials produced by catecholamines in guinea pig atrial muscle fibers depolarized by potassium. Circ Res. 1970 Sep;27(3):379–390. doi: 10.1161/01.res.27.3.379. [DOI] [PubMed] [Google Scholar]
  21. Prosser C. L. Rhythmic potentials in intestinal muscle. Fed Proc. 1978 Jun;37(8):2153–2157. [PubMed] [Google Scholar]
  22. Reid J. A., Hecht H. H. Barium-induced automaticity in right ventricular muscle in the dog. Circ Res. 1967 Dec;21(6):849–856. doi: 10.1161/01.res.21.6.849. [DOI] [PubMed] [Google Scholar]
  23. 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]
  24. Reuter H., Scholz H. A study of the ion selectivity and the kinetic properties of the calcium dependent slow inward current in mammalian cardiac muscle. J Physiol. 1977 Jan;264(1):17–47. doi: 10.1113/jphysiol.1977.sp011656. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Sakamoto Y., Goto M. A study of the membrane constants in the dog myocardium. Jpn J Physiol. 1970 Feb 15;20(1):30–41. doi: 10.2170/jjphysiol.20.30. [DOI] [PubMed] [Google Scholar]
  26. Sakamoto Y. Membrane characteristics of the canine papillary muscle fiber. J Gen Physiol. 1969 Dec;54(6):765–781. doi: 10.1085/jgp.54.6.765. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Sperelakis N., Lehmkuhl D. Ionic interconversion of pacemaker and nonpacemaker cultured chick heart cells. J Gen Physiol. 1966 May;49(5):867–895. doi: 10.1085/jgp.49.5.867. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Sperelakis N., Schneider M. F., Harris E. J. Decreased K+ conductance produced by Ba++ in frog sartorius fibers. J Gen Physiol. 1967 Jul;50(6):1565–1583. doi: 10.1085/jgp.50.6.1565. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Toda N. Barium-induced automaticity in relation to calcium ions and norepinephrine in the rabbit left atrium. Circ Res. 1970 Jul;27(1):45–57. doi: 10.1161/01.res.27.1.45. [DOI] [PubMed] [Google Scholar]
  30. WEIDMANN S. The effect of the cardiac membrane potential on the rapid availability of the sodium-carrying system. J Physiol. 1955 Jan 28;127(1):213–224. doi: 10.1113/jphysiol.1955.sp005250. [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. WEIDMANN S. The electrical constants of Purkinje fibres. J Physiol. 1952 Nov;118(3):348–360. doi: 10.1113/jphysiol.1952.sp004799. [DOI] [PMC free article] [PubMed] [Google Scholar]
  32. WRIGHT E. B., OGATA M. Action potential of amphibian single auricular muscle fiber: a dual response. Am J Physiol. 1961 Dec;201:1101–1108. doi: 10.1152/ajplegacy.1961.201.6.1101. [DOI] [PubMed] [Google Scholar]
  33. Weidmann S. Electrical constants of trabecular muscle from mammalian heart. J Physiol. 1970 Nov;210(4):1041–1054. doi: 10.1113/jphysiol.1970.sp009256. [DOI] [PMC free article] [PubMed] [Google Scholar]
  34. de Carvalho A. P., Hoffman B. F., de Carvalho M. P. Two components of the cardiac action potential. I. Voltage-time course and the effect of acetylcholine on atrial and nodal cells of the rabbit heart. J Gen Physiol. 1969 Nov;54(5):607–635. doi: 10.1085/jgp.54.5.607. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from The Journal of General Physiology are provided here courtesy of The Rockefeller University Press

RESOURCES