Skip to main content
PMC home page
The Journal of Physiology logoLink to The Journal of Physiology
. 1992 Apr;449:689–704. doi: 10.1113/jphysiol.1992.sp019109

Isoprenaline, Ca2+ and the Na(+)-K+ pump in guinea-pig ventricular myocytes.

J Gao 1, R T Mathias 1, I S Cohen 1, G J Baldo 1
PMCID: PMC1176102  PMID: 1326051

Abstract

1. The whole-cell patch clamp technique was employed to study the effects of the beta-agonist isoprenaline (ISO) on the Na(+)=K+ pump current, Ip, in acutely isolated ventricular myocytes from guinea-pig hearts. Propranolol, a beta-adrenergic antagonist, was used to demonstrate that all of the effects of ISO, stimulatory or inhibitory, are mediated by beta-receptors. 2. Below about 150 nM [Ca2+]i, we find that ISO reduces Ip, while above this [Ca2+]i ISO increases Ip. The stimulatory and inhibitory effects of ISO on Ip are independent of either intracellular sodium ([Na+]i) or extracellular potassium ([K+]o). These results suggest that the end-effect of ISO is directly on the maximum pump turnover rate (Vmax) rather than indirectly through changes in [Na+]i or [K+]o or modulatory effects on Na+ or K+ affinity. 3. The maximum effect of ISO increases Ip by 25% when [Ca2+] is buffered at 1.4 microM. A half-maximal effect is reached at roughly 10 nM-ISO and a near-maximal effect by 0.5 microM. 4. The permeabilized patch technique, using amphotericin B (Horn & Marty, 1988; Rae, Cooper, Gates & Watsky, 1991), was employed to minimize changes in the normal second messenger systems and calcium buffers. In these experiments, we used a high intracellular sodium solution (pipette sodium was 50 mM), thus sodium-calcium exchange was depressed and we expected [Ca2+]i to be above 150 nM. ISO increases Ip in these conditions as in the dialysed cells. 5. Our results suggest that beta-stimulation can increase Ip, but only if [Ca2+]i is above about 150 nM. In the beating heart [Ca2+]i rises well above this value during systole and the average [Ca2+]i, which depends on heart rate, is expected to normally be above this level. During beta-stimulation, the increase in Ip along with a concomitant increase in IK (Giles, Nakajima, Ono & Shibata, 1989; Duchatelle-Gourdon, Hartzell & Lagrutta, 1989) helps prevent action potential lengthening and allows an increase in heart rate even in the presence of increased calcium current. Further, beta-stimulation will compensate for the effects on Ip of either hypokalaemia or digitalis toxicity, and so reduce the expected rise in both [Na+]i and [Ca2+]i.

Full text

PDF
701

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Bahinski A., Nairn A. C., Greengard P., Gadsby D. C. Chloride conductance regulated by cyclic AMP-dependent protein kinase in cardiac myocytes. Nature. 1989 Aug 31;340(6236):718–721. doi: 10.1038/340718a0. [DOI] [PubMed] [Google Scholar]
  2. Berthon B., Capiod T., Claret M. Effects of noradrenaline, vasopressin and angiotensin on the Na-K pump in rat isolated liver cells. Br J Pharmacol. 1985 Sep;86(1):151–161. doi: 10.1111/j.1476-5381.1985.tb09445.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Brum G., Osterrieder W., Trautwein W. Beta-adrenergic increase in the calcium conductance of cardiac myocytes studied with the patch clamp. Pflugers Arch. 1984 Jun;401(2):111–118. doi: 10.1007/BF00583870. [DOI] [PubMed] [Google Scholar]
  4. Chang D. C., Reese T. S. Changes in membrane structure induced by electroporation as revealed by rapid-freezing electron microscopy. Biophys J. 1990 Jul;58(1):1–12. doi: 10.1016/S0006-3495(90)82348-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Cohen I. S., Falk R. T., Mulrine N. K. Actions of barium and rubidium on membrane currents in canine Purkinje fibres. J Physiol. 1983 May;338:589–612. doi: 10.1113/jphysiol.1983.sp014691. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Daut J., Rüdel R. The electrogenic sodium pump in guinea-pig ventricular muscle: inhibition of pump current by cardiac glycosides. J Physiol. 1982 Sep;330:243–264. doi: 10.1113/jphysiol.1982.sp014339. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. De Weer P., Gadsby D. C., Rakowski R. F. Voltage dependence of the Na-K pump. Annu Rev Physiol. 1988;50:225–241. doi: 10.1146/annurev.ph.50.030188.001301. [DOI] [PubMed] [Google Scholar]
  8. DiFrancesco D. Characterization of single pacemaker channels in cardiac sino-atrial node cells. Nature. 1986 Dec 4;324(6096):470–473. doi: 10.1038/324470a0. [DOI] [PubMed] [Google Scholar]
  9. Duchatelle-Gourdon I., Hartzell H. C., Lagrutta A. A. Modulation of the delayed rectifier potassium current in frog cardiomyocytes by beta-adrenergic agonists and magnesium. J Physiol. 1989 Aug;415:251–274. doi: 10.1113/jphysiol.1989.sp017721. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Désilets M., Baumgarten C. M. Isoproterenol directly stimulates the Na+-K+ pump in isolated cardiac myocytes. Am J Physiol. 1986 Jul;251(1 Pt 2):H218–H225. doi: 10.1152/ajpheart.1986.251.1.H218. [DOI] [PubMed] [Google Scholar]
  11. Egan T. M., Noble D., Noble S. J., Powell T., Twist V. W., Yamaoka K. On the mechanism of isoprenaline- and forskolin-induced depolarization of single guinea-pig ventricular myocytes. J Physiol. 1988 Jun;400:299–320. doi: 10.1113/jphysiol.1988.sp017121. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Fabiato A. Computer programs for calculating total from specified free or free from specified total ionic concentrations in aqueous solutions containing multiple metals and ligands. Methods Enzymol. 1988;157:378–417. doi: 10.1016/0076-6879(88)57093-3. [DOI] [PubMed] [Google Scholar]
  13. Falk R. T., Cohen I. S. Membrane current following activity in canine cardiac Purkinje fibers. J Gen Physiol. 1984 May;83(5):771–799. doi: 10.1085/jgp.83.5.771. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Gadsby D. C. Beta-adrenoceptor agonists increase membrane K+ conductance in cardiac Purkinje fibres. Nature. 1983 Dec 15;306(5944):691–693. doi: 10.1038/306691a0. [DOI] [PubMed] [Google Scholar]
  15. Gadsby D. C., Nakao M. Steady-state current-voltage relationship of the Na/K pump in guinea pig ventricular myocytes. J Gen Physiol. 1989 Sep;94(3):511–537. doi: 10.1085/jgp.94.3.511. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Giles W., Nakajima T., Ono K., Shibata E. F. Modulation of the delayed rectifier K+ current by isoprenaline in bull-frog atrial myocytes. J Physiol. 1989 Aug;415:233–249. doi: 10.1113/jphysiol.1989.sp017720. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Glitsch H. G., Krahn T., Pusch H., Suleymanian M. Effect of isoprenaline on active Na transport in sheep cardiac Purkinje fibres. Pflugers Arch. 1989 Oct;415(1):88–94. doi: 10.1007/BF00373145. [DOI] [PubMed] [Google Scholar]
  18. Hamill O. P., Marty A., Neher E., Sakmann B., Sigworth F. J. Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflugers Arch. 1981 Aug;391(2):85–100. doi: 10.1007/BF00656997. [DOI] [PubMed] [Google Scholar]
  19. Harvey R. D., Hume J. R. Autonomic regulation of a chloride current in heart. Science. 1989 May 26;244(4907):983–985. doi: 10.1126/science.2543073. [DOI] [PubMed] [Google Scholar]
  20. Horn R., Marty A. Muscarinic activation of ionic currents measured by a new whole-cell recording method. J Gen Physiol. 1988 Aug;92(2):145–159. doi: 10.1085/jgp.92.2.145. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Isenberg G., Klöckner U. Calcium currents of isolated bovine ventricular myocytes are fast and of large amplitude. Pflugers Arch. 1982 Oct;395(1):30–41. doi: 10.1007/BF00584965. [DOI] [PubMed] [Google Scholar]
  22. Isenberg G., Trautwein W. The effect of dihydro-ouabain and lithium-ions on the outward current in cardiac Purkinje fibers. Evidence for electrogenicity of active transport. Pflugers Arch. 1974;350(1):41–54. doi: 10.1007/BF00586737. [DOI] [PubMed] [Google Scholar]
  23. Mogul D. J., Rasmussen H. H., Singer D. H., Ten Eick R. E. Inhibition of Na-K pump current in guinea pig ventricular myocytes by dihydroouabain occurs at high- and low-affinity sites. Circ Res. 1989 Jun;64(6):1063–1069. doi: 10.1161/01.res.64.6.1063. [DOI] [PubMed] [Google Scholar]
  24. Nairn A. C., Hemmings H. C., Jr, Greengard P. Protein kinases in the brain. Annu Rev Biochem. 1985;54:931–976. doi: 10.1146/annurev.bi.54.070185.004435. [DOI] [PubMed] [Google Scholar]
  25. Nakao M., Gadsby D. C. [Na] and [K] dependence of the Na/K pump current-voltage relationship in guinea pig ventricular myocytes. J Gen Physiol. 1989 Sep;94(3):539–565. doi: 10.1085/jgp.94.3.539. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Nakayama T., Palfrey C., Fozzard H. A. Modulation of the cardiac transient outward current by catecholamines. J Mol Cell Cardiol. 1989 Feb;21 (Suppl 1):109–118. doi: 10.1016/0022-2828(89)90845-6. [DOI] [PubMed] [Google Scholar]
  27. Oliva C., Cohen I. S., Mathias R. T. Calculation of time constants for intracellular diffusion in whole cell patch clamp configuration. Biophys J. 1988 Nov;54(5):791–799. doi: 10.1016/S0006-3495(88)83017-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Rae J., Cooper K., Gates P., Watsky M. Low access resistance perforated patch recordings using amphotericin B. J Neurosci Methods. 1991 Mar;37(1):15–26. doi: 10.1016/0165-0270(91)90017-t. [DOI] [PubMed] [Google Scholar]
  29. Schubert B., VanDongen A. M., Kirsch G. E., Brown A. M. Beta-adrenergic inhibition of cardiac sodium channels by dual G-protein pathways. Science. 1989 Aug 4;245(4917):516–519. doi: 10.1126/science.2547248. [DOI] [PubMed] [Google Scholar]
  30. Schweigert B., Lafaire A. V., Schwarz W. Voltage dependence of the Na-K ATPase: measurements of ouabain-dependent membrane current and ouabain binding in oocytes of Xenopus laevis. Pflugers Arch. 1988 Oct;412(6):579–588. doi: 10.1007/BF00583758. [DOI] [PubMed] [Google Scholar]
  31. Tromba C., Cohen I. S. A novel action of isoproterenol to inactivate a cardiac K+ current is not blocked by beta and alpha adrenergic blockers. Biophys J. 1990 Sep;58(3):791–795. doi: 10.1016/S0006-3495(90)82422-X. [DOI] [PMC free article] [PubMed] [Google Scholar]
  32. Tsien R. W. Effects of epinephrine on the pacemaker potassium current of cardiac Purkinje fibers. J Gen Physiol. 1974 Sep;64(3):293–319. doi: 10.1085/jgp.64.3.293. [DOI] [PMC free article] [PubMed] [Google Scholar]
  33. Vassalle M., Barnabei O. Norepinephrine and potassium fluxes in cardiac Purkinje fibers. Pflugers Arch. 1971;322(4):287–303. doi: 10.1007/BF00587747. [DOI] [PubMed] [Google Scholar]
  34. Yingst D. R. Modulation of the Na,K-ATPase by Ca and intracellular proteins. Annu Rev Physiol. 1988;50:291–303. doi: 10.1146/annurev.ph.50.030188.001451. [DOI] [PubMed] [Google Scholar]

Articles from The Journal of Physiology are provided here courtesy of The Physiological Society

RESOURCES