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. 1993 Feb;461:263–281. doi: 10.1113/jphysiol.1993.sp019513

Activation of muscarinic K+ current in guinea-pig atrial myocytes by a serum factor.

K Banach 1, J Hüser 1, P Lipp 1, M C Wellner 1, L Pott 1
PMCID: PMC1175257  PMID: 8350265

Abstract

1. Atrial myocytes obtained by enzymatic perfusion of hearts from adult guinea-pigs and cultured for 0-14 days were studied using the whole-cell voltage-clamp technique. 2. Superfusion of the myocytes with diluted sera (1:100 to 1:10,000) from different species (human, horse, guinea-pig) evoked an inward rectifying K+ current. The voltage-dependent properties of this current were identical to those of the K+ current activated by acetylcholine (IK(ACh)). Current density in the presence of horse serum (1:100) approximately corresponded to the non-desensitizing fraction of IK(ACh) during superfusion with 1-2 x 10(-6) M ACh. 3. During a maximal serum-evoked current, application of ACh (10(-6) M) failed to evoke additional K+ current. After switching superfusion from serum-containing to serum-free solution, the K+ current decayed 1-2 orders of magnitude slower than ACh-activated IK(ACh). During the decay of the serum-evoked current, a proportional increase in responsiveness to ACh was recorded. During submaximal activation of K+ current by serum, a saturating concentration of ACh resulted in a total current that was identical to the current evoked by ACh alone minus the desensitizing component. Thus, activation of K+ current by serum caused desensitization of IK(ACh). From these results it is concluded that sera contain a factor that activates the same population of K+ channels as ACh. 4. Irreversible activation of IK(ACh) by ACh in myocytes dialysed with the GTP-analogue GTP-gamma-S abolished sensitivity to serum and vice versa. 5. The effect of serum was not modified by atropine (10(-6) M) which completely blocked the response to 2 x 10(-6) M ACh. Furthermore, theophylline (1 mM), which completely inhibited IK(ACh) activation by adenosine (100 microM), failed to inhibit the effect of serum. Thus, neither muscarinic nor purinergic (A1) receptors are involved. 6. The peptide somatostatin (10(-6) M) and the alpha 1-agonist phenylephrine (1 microM) which previously have been shown to cause activation of IK(ACh) channels, in the present study failed to evoke any measurable current, which excludes the involvement of the corresponding receptors. 7. Pre-incubation of the cells with pertussis toxin completely abolished IK(ACh) evoked by ACh, adenosine and serum, suggesting that the activating factor, like the classical agonists, causes opening of IK(ACh) channels via a G protein (Gi, GK). 8. The potency of serum to activate IK(ACh) was not reduced by dialysis, suggesting the molecular mass of the unknown factor to be > or = 5 kDa. No activating potency was found in the dialysing solutions.(ABSTRACT TRUNCATED AT 400 WORDS)

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Selected References

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  1. Bechem M., Pott L., Rennebaum H. Atrial muscle cells from hearts of adult guinea-pigs in culture: a new preparation for cardiac cellular electrophysiology. Eur J Cell Biol. 1983 Sep;31(2):366–369. [PubMed] [Google Scholar]
  2. Belardinelli L., Giles W. R., West A. Ionic mechanisms of adenosine actions in pacemaker cells from rabbit heart. J Physiol. 1988 Nov;405:615–633. doi: 10.1113/jphysiol.1988.sp017352. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Belardinelli L., Isenberg G. Isolated atrial myocytes: adenosine and acetylcholine increase potassium conductance. Am J Physiol. 1983 May;244(5):H734–H737. doi: 10.1152/ajpheart.1983.244.5.H734. [DOI] [PubMed] [Google Scholar]
  4. Breitwieser G. E., Szabo G. Uncoupling of cardiac muscarinic and beta-adrenergic receptors from ion channels by a guanine nucleotide analogue. Nature. 1985 Oct 10;317(6037):538–540. doi: 10.1038/317538a0. [DOI] [PubMed] [Google Scholar]
  5. Cerbai E., Klöckner U., Isenberg G. The alpha subunit of the GTP binding protein activates muscarinic potassium channels of the atrium. Science. 1988 Jun 24;240(4860):1782–1783. doi: 10.1126/science.2454511. [DOI] [PubMed] [Google Scholar]
  6. DiFrancesco D., Tromba C. Muscarinic control of the hyperpolarization-activated current (if) in rabbit sino-atrial node myocytes. J Physiol. 1988 Nov;405:493–510. doi: 10.1113/jphysiol.1988.sp017344. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Giles W. R., Imaizumi Y. Comparison of potassium currents in rabbit atrial and ventricular cells. J Physiol. 1988 Nov;405:123–145. doi: 10.1113/jphysiol.1988.sp017325. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Glitsch H. G., Pott L. Effects of acetylcholine and parasympathetic nerve stimulation on membrane potential in quiescent guinea-pig atria. J Physiol. 1978 Jun;279:655–668. doi: 10.1113/jphysiol.1978.sp012367. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. HUTTER O. F. Mode of action of autonomic transmitters on the heart. Br Med Bull. 1957 Sep;13(3):176–180. doi: 10.1093/oxfordjournals.bmb.a069609. [DOI] [PubMed] [Google Scholar]
  10. Hallström S., Koidl B., Müller U., Werdan K., Schlag G. A cardiodepressant factor isolated from blood blocks Ca2+ current in cardiomyocytes. Am J Physiol. 1991 Mar;260(3 Pt 2):H869–H876. doi: 10.1152/ajpheart.1991.260.3.H869. [DOI] [PubMed] [Google Scholar]
  11. 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]
  12. Hartzell H. C. Regulation of cardiac ion channels by catecholamines, acetylcholine and second messenger systems. Prog Biophys Mol Biol. 1988;52(3):165–247. doi: 10.1016/0079-6107(88)90014-4. [DOI] [PubMed] [Google Scholar]
  13. Horie M., Irisawa H. Rectification of muscarinic K+ current by magnesium ion in guinea pig atrial cells. Am J Physiol. 1987 Jul;253(1 Pt 2):H210–H214. doi: 10.1152/ajpheart.1987.253.1.H210. [DOI] [PubMed] [Google Scholar]
  14. Iijima T., Irisawa H., Kameyama M. Membrane currents and their modification by acetylcholine in isolated single atrial cells of the guinea-pig. J Physiol. 1985 Feb;359:485–501. doi: 10.1113/jphysiol.1985.sp015598. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Kaibara M., Nakajima T., Irisawa H., Giles W. Regulation of spontaneous opening of muscarinic K+ channels in rabbit atrium. J Physiol. 1991 Feb;433:589–613. doi: 10.1113/jphysiol.1991.sp018445. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Kim D. Calcitonin-gene-related peptide activates the muscarinic-gated K+ current in atrial cells. Pflugers Arch. 1991 May;418(4):338–345. doi: 10.1007/BF00550871. [DOI] [PubMed] [Google Scholar]
  17. Kim D. Endothelin activation of an inwardly rectifying K+ current in atrial cells. Circ Res. 1991 Jul;69(1):250–255. doi: 10.1161/01.res.69.1.250. [DOI] [PubMed] [Google Scholar]
  18. Kim D., Lewis D. L., Graziadei L., Neer E. J., Bar-Sagi D., Clapham D. E. G-protein beta gamma-subunits activate the cardiac muscarinic K+-channel via phospholipase A2. Nature. 1989 Feb 9;337(6207):557–560. doi: 10.1038/337557a0. [DOI] [PubMed] [Google Scholar]
  19. Kirsch G. E., Yatani A., Codina J., Birnbaumer L., Brown A. M. Alpha-subunit of Gk activates atrial K+ channels of chick, rat, and guinea pig. Am J Physiol. 1988 Jun;254(6 Pt 2):H1200–H1205. doi: 10.1152/ajpheart.1988.254.6.H1200. [DOI] [PubMed] [Google Scholar]
  20. Kurachi Y., Ito H., Sugimoto T., Shimizu T., Miki I., Ui M. Alpha-adrenergic activation of the muscarinic K+ channel is mediated by arachidonic acid metabolites. Pflugers Arch. 1989 May;414(1):102–104. doi: 10.1007/BF00585635. [DOI] [PubMed] [Google Scholar]
  21. Kurachi Y., Nakajima T., Sugimoto T. On the mechanism of activation of muscarinic K+ channels by adenosine in isolated atrial cells: involvement of GTP-binding proteins. Pflugers Arch. 1986 Sep;407(3):264–274. doi: 10.1007/BF00585301. [DOI] [PubMed] [Google Scholar]
  22. Kurachi Y., Nakajima T., Sugimoto T. Short-term desensitization of muscarinic K+ channel current in isolated atrial myocytes and possible role of GTP-binding proteins. Pflugers Arch. 1987 Oct;410(3):227–233. doi: 10.1007/BF00580270. [DOI] [PubMed] [Google Scholar]
  23. Lewis D. L., Clapham D. E. Somatostatin activates an inwardly rectifying K+ channel in neonatal rat atrial cells. Pflugers Arch. 1989 Aug;414(4):492–494. doi: 10.1007/BF00585062. [DOI] [PubMed] [Google Scholar]
  24. Logothetis D. E., Kurachi Y., Galper J., Neer E. J., Clapham D. E. The beta gamma subunits of GTP-binding proteins activate the muscarinic K+ channel in heart. Nature. 1987 Jan 22;325(6102):321–326. doi: 10.1038/325321a0. [DOI] [PubMed] [Google Scholar]
  25. Mattera R., Yatani A., Kirsch G. E., Graf R., Okabe K., Olate J., Codina J., Brown A. M., Birnbaumer L. Recombinant alpha i-3 subunit of G protein activates Gk-gated K+ channels. J Biol Chem. 1989 Jan 5;264(1):465–471. [PubMed] [Google Scholar]
  26. Milligan G. Techniques used in the identification and analysis of function of pertussis toxin-sensitive guanine nucleotide binding proteins. Biochem J. 1988 Oct 1;255(1):1–13. doi: 10.1042/bj2550001. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Noma A., Nakayama T., Kurachi Y., Irisawa H. Resting K conductances in pacemaker and non-pacemaker heart cells of the rabbit. Jpn J Physiol. 1984;34(2):245–254. doi: 10.2170/jjphysiol.34.245. [DOI] [PubMed] [Google Scholar]
  28. Okabe K., Yatani A., Brown A. M. The nature and origin of spontaneous noise in G protein-gated ion channels. J Gen Physiol. 1991 Jun;97(6):1279–1293. doi: 10.1085/jgp.97.6.1279. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Okabe K., Yatani A., Evans T., Ho Y. K., Codina J., Birnbaumer L., Brown A. M. Beta gamma dimers of G proteins inhibit atrial muscarinic K+ channels. J Biol Chem. 1990 Aug 5;265(22):12854–12858. [PubMed] [Google Scholar]
  30. Pfaffinger P. J., Martin J. M., Hunter D. D., Nathanson N. M., Hille B. GTP-binding proteins couple cardiac muscarinic receptors to a K channel. Nature. 1985 Oct 10;317(6037):536–538. doi: 10.1038/317536a0. [DOI] [PubMed] [Google Scholar]
  31. Pott L., Pusch H. A kinetic model for the muscarinic action of acetylcholine. Pflugers Arch. 1979 Dec;383(1):75–77. doi: 10.1007/BF00584478. [DOI] [PubMed] [Google Scholar]
  32. Sakmann B., Noma A., Trautwein W. Acetylcholine activation of single muscarinic K+ channels in isolated pacemaker cells of the mammalian heart. Nature. 1983 May 19;303(5914):250–253. doi: 10.1038/303250a0. [DOI] [PubMed] [Google Scholar]
  33. Sorota S., Hoffman B. F. Role of G proteins in the acetylcholine-induced potassium current of canine atrial cells. Am J Physiol. 1989 Nov;257(5 Pt 2):H1516–H1522. doi: 10.1152/ajpheart.1989.257.5.H1516. [DOI] [PubMed] [Google Scholar]
  34. Szabo G., Otero A. S. G protein mediated regulation of K+ channels in heart. Annu Rev Physiol. 1990;52:293–305. doi: 10.1146/annurev.ph.52.030190.001453. [DOI] [PubMed] [Google Scholar]
  35. TRAUTWEIN W., DUDEL J. Zum Mechanismus der Membranwirkung des Acetylcholin an der Herzmuskelfaser. Pflugers Arch. 1958;266(3):324–334. doi: 10.1007/BF00416781. [DOI] [PubMed] [Google Scholar]
  36. Tigyi G., Henschen A., Miledi R. A factor that activates oscillatory chloride currents in Xenopus oocytes copurifies with a subfraction of serum albumin. J Biol Chem. 1991 Nov 5;266(31):20602–20609. [PubMed] [Google Scholar]
  37. Xuan Y. T., Whorton A. R., Shearer-Poor E., Boyd J., Watkins W. D. Determination of immunoreactive endothelin in medium from cultured endothelial cells and human plasma. Biochem Biophys Res Commun. 1989 Oct 16;164(1):326–332. doi: 10.1016/0006-291x(89)91721-x. [DOI] [PubMed] [Google Scholar]

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