| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
1. The dependence of gap junctional conductance on the intracellular concentrations of H+, Ca2+ and Mg2+ was studied in paired myocytes dissociated enzymatically from guinea-pig ventricle. To apply an internal solution buffered to specific H+, Ca2+ or Mg2+ concentration directly to one aspect of the gap junction, the non-junctional membrane of one of the pair was mechanically ruptured. The junctional conductance was measured by clamping the membrane potential of the other cell using a two-pipette voltage-clamp method. 2. The conductance of the non-junctional membrane was kept low in comparison with that of the junctional membrane (less than 1/50) by replacing both external and internal K+ with Cs+. 3. The current-voltage (I-V) relation of the junctional conductance was linear over the potential range examined (from -100 to +100 mV). No voltage or time dependence was detected. 4. The conductance of the gap junction between the paired cells ranged from 90 to 3900 nS with a peak distribution at 1000 nS. 5. The effect of H+ was examined over the pH range 7.4-5.4, while keeping the free-Ca2+ concentration at zero, or pCa 6.3 or 7.0 using 2-10 mM-EGTA. The junctional conductance was almost constant from pH 7.4 to 6.5 and decreased in a dose-dependent manner with further acidification. There was no difference in the pH-conductance relationships at various Ca2+ concentrations. The Hill coefficient was approximately 2.4 and the half-maximum concentration (pK'H) was 6.1. 6. The closing effect of Ca2+ on the gap junction channel was examined over the concentration range from pCa 7 to 5, while keeping the pH at 7.4, 7.0 or 6.5. At each pH, increasing Ca2+ decreased the junctional conductance with similar Hill coefficients of about 3.4. The pCa-conductance relationship shifted toward a higher Ca2+ concentration range as the pH was lowered (pK'Ca = 6.6, 6.4 and 5.6, at pH 7.4, 7.0 and 6.5, respectively). 7. Increasing Mg2+ also caused a fall in the junctional conductance over the pMg range 3.0-2.0 with a pK'Mg of 2.5 (3.2 mM), and a Hill coefficient of 3.0. 8. These results suggest that there are two respective binding sites for divalent cations and H+, and that the gap junctional conductance is regulated reversibly by the ligand-receptor reactions. Comparing the threshold concentrations of Ca2+ and H+ for electrical uncoupling, it was concluded that Ca2+ plays a more important role in regulating the gap junctional conductance of cardiac cells under physiological conditions.
This article has been cited by other articles:
|
|
 |
|
  D. J. Muller, N. Wu, and K. Palczewski Vertebrate Membrane Proteins: Structure, Function, and Insights from Biophysical Approaches Pharmacol. Rev., March 1, 2008; 60(1): 43 - 78. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. M. Lurtz and C. F. Louis Intracellular calcium regulation of connexin43 Am J Physiol Cell Physiol, December 1, 2007; 293(6): C1806 - C1813. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Zhou, W. Yang, M. M. Lurtz, Y. Ye, Y. Huang, H.-W. Lee, Y. Chen, C. F. Louis, and J. J. Yang Identification of the Calmodulin Binding Domain of Connexin 43 J. Biol. Chem., November 30, 2007; 282(48): 35005 - 35017. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 V. E. Bondarenko and R. L. Rasmusson Simulations of propagated mouse ventricular action potentials: effects of molecular heterogeneity Am J Physiol Heart Circ Physiol, September 1, 2007; 293(3): H1816 - H1832. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Swietach, A. Rossini, K. W. Spitzer, and R. D. Vaughan-Jones H+ Ion Activation and Inactivation of the Ventricular Gap Junction: A Basis for Spatial Regulation of Intracellular pH Circ. Res., April 13, 2007; 100(7): 1045 - 1054. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Yu, C. A. Bippes, G. M. Hand, D. J. Muller, and G. E. Sosinsky Aminosulfonate Modulated pH-induced Conformational Changes in Connexin26 Hemichannels J. Biol. Chem., March 23, 2007; 282(12): 8895 - 8904. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Swietach and R. D. Vaughan-Jones Novel method for measuring junctional proton permeation in isolated ventricular myocyte cell pairs Am J Physiol Heart Circ Physiol, November 1, 2004; 287(5): H2352 - H2363. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Fidzinski, M. Salvador-Silva, L. Choritz, J. Geibel, and M. Coca-Prados Inhibition of NHE-1 Na+/H+ exchanger by natriuretic peptides in ocular nonpigmented ciliary epithelium Am J Physiol Cell Physiol, September 1, 2004; 287(3): C655 - C663. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Rodriguez-Sinovas, D. Garcia-Dorado, M. Ruiz-Meana, and J. Soler-Soler Enhanced effect of gap junction uncouplers on macroscopic electrical properties of reperfused myocardium J. Physiol., August 15, 2004; 559(1): 245 - 257. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Dhein Pharmacology of gap junctions in the cardiovascular system Cardiovasc Res, May 1, 2004; 62(2): 287 - 298. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Schulz and G. Heusch Connexin 43 and ischemic preconditioning Cardiovasc Res, May 1, 2004; 62(2): 335 - 344. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Matsushita, Y. Sakakibara, T. Imazuru, M. Noma, Y. Hiramatsu, O. Shigeta, T. Jikuya, and T. Mitsui High-frequency QRS potentials as a marker of myocardial dysfunction after cardiac surgery Ann. Thorac. Surg., April 1, 2004; 77(4): 1293 - 1297. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. G. KLEBER and Y. RUDY Basic Mechanisms of Cardiac Impulse Propagation and Associated Arrhythmias Physiol Rev, April 1, 2004; 84(2): 431 - 488. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. Garcia-Dorado, A. Rodriguez-Sinovas, and M. Ruiz-Meana Gap junction-mediated spread of cell injury and death during myocardial ischemia-reperfusion Cardiovasc Res, February 15, 2004; 61(3): 386 - 401. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. C. Eloff, E. Gilat, X. Wan, and D. S. Rosenbaum Pharmacological Modulation of Cardiac Gap Junctions to Enhance Cardiac Conduction: Evidence Supporting a Novel Target for Antiarrhythmic Therapy Circulation, December 23, 2003; 108(25): 3157 - 3163. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Zaniboni, A. Rossini, P. Swietach, N. Banger, K. W. Spitzer, and R. D. Vaughan-Jones Proton Permeation Through the Myocardial Gap Junction Circ. Res., October 17, 2003; 93(8): 726 - 735. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J.-A. Yao, W. Hussain, P. Patel, N. S. Peters, P. A. Boyden, and A. L. Wit Remodeling of Gap Junctional Channel Function in Epicardial Border Zone of Healing Canine Infarcts Circ. Res., March 7, 2003; 92(4): 437 - 443. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. P Baader, L. Buchler, L. Bircher-Lehmann, and A. G Kleber Real time, confocal imaging of Ca2+ waves in arterially perfused rat hearts Cardiovasc Res, January 1, 2002; 53(1): 105 - 115. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. C. Churchill, M. M. Lurtz, and C. F. Louis Ca2+ regulation of gap junctional coupling in lens epithelial cells Am J Physiol Cell Physiol, September 1, 2001; 281(3): C972 - C981. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. O. Suadicani, M. J. Vink, and D. C. Spray Slow intercellular Ca2+ signaling in wild-type and Cx43-null neonatal mouse cardiac myocytes Am J Physiol Heart Circ Physiol, December 1, 2000; 279(6): H3076 - H3088. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Cabo, H. Schmitt, and A. L. Wit New Mechanism of Antiarrhythmic Drug Action : Increasing L-Type Calcium Current Prevents Reentrant Ventricular Tachycardia in the Infarcted Canine Heart Circulation, November 7, 2000; 102(19): 2417 - 2425. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. Taimor Cardiac gap junctions: good or bad? Cardiovasc Res, October 1, 2000; 48(1): 8 - 10. [Full Text] [PDF]
|
|
|
|
|
|
T. Kaneko, H. Tanaka, M. Oyamada, S. Kawata, and T. Takamatsu Three Distinct Types of Ca2+ Waves in Langendorff-Perfused Rat Heart Revealed by Real-Time Confocal Microscopy Circ. Res., May 26, 2000; 86(10): 1093 - 1099. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. G Kleber ST-segment elevation in the electrocardiogram: a sign of myocardial ischemia Cardiovasc Res, January 1, 2000; 45(1): 111 - 118. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Carmeliet Cardiac Ionic Currents and Acute Ischemia: From Channels to Arrhythmias Physiol Rev, July 1, 1999; 79(3): 917 - 1017. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. F. Tomaselli and E. Marban Electrophysiological remodeling in hypertrophy and heart failure Cardiovasc Res, May 1, 1999; 42(2): 270 - 283. [Full Text] [PDF]
|
|
|
|
 |
|
 G. Bub, L. Glass, N. G. Publicover, and A. Shrier Bursting calcium rotors in cultured cardiac myocyte monolayers PNAS, August 18, 1998; 95(17): 10283 - 10287. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. S. Peters and A. L. Wit Myocardial Architecture and Ventricular Arrhythmogenesis Circulation, May 5, 1998; 97(17): 1746 - 1754. [Full Text] [PDF]
|
|
|
|
|
|
J. Cinca, M. Warren, A. Carreno, M. Tresanchez, L. Armadans, P. Gomez, and J. Soler-Soler Changes in Myocardial Electrical Impedance Induced by Coronary Artery Occlusion in Pigs With and Without Preconditioning : Correlation With Local ST-Segment Potential and Ventricular Arrhythmias Circulation, November 4, 1997; 96(9): 3079 - 3086. [Abstract] [Full Text]
|
|
|
|
|
|
R. M. Shaw and Y. Rudy Electrophysiologic Effects of Acute Myocardial Ischemia: A Mechanistic Investigation of Action Potential Conduction and Conduction Failure Circ. Res., January 1, 1997; 80(1): 124 - 138. [Abstract] [Full Text]
|
|
|
|
|
|
R. Kumar, R. Wilders, R. W. Joyner, H. J. Jongsma, E. E. Verheijck, D. A. Golod, A. C.G. van Ginneken, and W. N. Goolsby Experimental Model for an Ectopic Focus Coupled to Ventricular Cells Circulation, August 15, 1996; 94(4): 833 - 841. [Abstract] [Full Text]
|
|
|
|
|
|
L. R.C. Dekker, J. W.T. Fiolet, E. VanBavel, R. Coronel, T. Opthof, J. A.E. Spaan, and M. J. Janse Intracellular Ca2+, Intercellular Electrical Coupling, and Mechanical Activity in Ischemic Rabbit Papillary Muscle: Effects of Preconditioning and Metabolic Blockade Circ. Res., August 1, 1996; 79(2): 237 - 246. [Abstract] [Full Text]
|
|
|
|
|
|
L. M. Owens, T. A. Fralix, E. Murphy, W. E. Cascio, and L. S. Gettes Correlation of Ischemia-Induced Extracellular and Intracellular Ion Changes to Cell-to-Cell Electrical Uncoupling in Isolated Blood-Perfused Rabbit Hearts Circulation, July 1, 1996; 94(1): 10 - 13. [Abstract] [Full Text]
|
|
|
|
|
|
W. T. Smith, W. F. Fleet, T. A. Johnson, C. L. Engle, and W. E. Cascio The Ib Phase of Ventricular Arrhythmias in Ischemic In Situ Porcine Heart Is Related to Changes in Cell-to-Cell Electrical Coupling Circulation, November 15, 1995; 92(10): 3051 - 3060. [Abstract] [Full Text]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
