Biophysical Journal 65: 2002-2012 (1993)
© 1993 the Biophysical Society

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Lazrak, A Articles by Peracchia, C Search for Related Content PubMed PubMed Citation Articles by Lazrak, A Articles by Peracchia, C

Gap junction gating sensitivity to physiological internal calcium regardless of pH in Novikoff hepatoma cells.

Department of Physiology, University of Rochester, New York 14642-8642.

ABSTRACT

Gap junction conductance (Gj) and channel gating sensitivity to voltage, Ca2+, H+, and heptanol were studied by double whole-cell clamp in Novikoff hepatoma cell pairs. Channel gating was observed at transjunctional voltages (Vj) > +/- 50 mV. The cells readily uncoupled with 1 mM 1-heptanol. With heptanol, single (gap junctional) channel events with unitary conductances (gamma j) of 46 and 97 pS were detected. Both Ca(2+)-loading (EGTA.Ca) and acidifying (100% CO2) solutions caused uncoupling. However, CO2 was effective when Ca2+i was buffered with EGTA (a H(+)-sensitive Ca-buffer) but not with BAPTA (1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid) (a H(+)-insensitive Ca-buffer), suggesting a Ca(2+)-mediated H+ effect on gap junctions. This was tested by monitoring the Gj decay at different pCai values (9, 6.9, 6.3, 6, and 5.5; 1 mM BAPTA) and pHi values (7.2 or 6.1, 10 mM 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid and 2-(N-morpholino)ethansulphonic acid, respectively). With pCai > or = 6.9 (pH 7.2 or 6.1), Gj decreased to 10-70% of initial values in approximately 40 min, following single exponential decays (tau = approximately 28 min). With pCai 6-6.3 (pH 7.2 or 6.1), Gj decreased to 10-25% of initial values in 15 min (tau = approximately 5 min); the Student t gave a P = 0.0178. With pCa 5.5 the cells uncoupled in less than 1 min (tau = approximately 20 s). Low pHi affected neither time course nor shape of Gj decay at any pCai tested. The data indicate that these gap junctions are sensitive to [Ca2+]i in the physiological range (< or = 500 nM) and that low pHi, without an increase in [Ca2+]i, neither decreases Gj nor increases channel sensitivity to Ca2+.

This article has been cited by other articles:

				N. Kurebayashi, H. Nishizawa, Y. Nakazato, H. Kurihara, S. Matsushita, H. Daida, and Y. Ogawa Aberrant cell-to-cell coupling in Ca2+-overloaded guinea pig ventricular muscles Am J Physiol Cell Physiol, June 1, 2008; 294(6): C1419 - C1429. [Abstract] [Full Text] [PDF]

				L. L. Colgin, D. Kubota, F. A. Brucher, Y. Jia, E. Branyan, C. M. Gall, and G. Lynch Spontaneous Waves in the Dentate Gyrus of Slices From the Ventral Hippocampus J Neurophysiol, December 1, 2004; 92(6): 3385 - 3398. [Abstract] [Full Text] [PDF]

				A. Lazrak and S. Matalon cAMP-induced changes of apical membrane potentials of confluent H441 monolayers Am J Physiol Lung Cell Mol Physiol, August 1, 2003; 285(2): L443 - L450. [Abstract] [Full Text] [PDF]

				V. Abudara, R. G. Jiang, and C. Eyzaguirre Behavior of Junction Channels Between Rat Glomus Cells During Normoxia and Hypoxia J Neurophysiol, August 1, 2002; 88(2): 639 - 649. [Abstract] [Full Text] [PDF]

				S. Fritz, L. Kunz, N. Dimitrijevic, R. Grunert, C. Heiss, and A. Mayerhofer Muscarinic Receptors in Human Luteinized Granulosa Cells: Activation Blocks Gap Junctions and Induces the Transcription Factor Early Growth Response Factor-1 J. Clin. Endocrinol. Metab., March 1, 2002; 87(3): 1362 - 1367. [Abstract] [Full Text] [PDF]

				T. E. Ludwig, J. M. Squirrell, A. C. Palmenberg, and B. D. Bavister Relationship Between Development, Metabolism, and Mitochondrial Organization in 2-Cell Hamster Embryos in the Presence of Low Levels of Phosphate Biol Reprod, December 1, 2001; 65(6): 1648 - 1654. [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]

				C. Clair, C. Chalumeau, T. Tordjmann, J. Poggioli, C. Erneux, G. Dupont, and L. Combettes Investigation of the roles of Ca2+ and InsP3 diffusion in the coordination of Ca2+ signals between connected hepatocytes J. Cell Sci., January 6, 2001; 114(11): 1999 - 2007. [Abstract] [Full Text] [PDF]

				A. Lazrak, A. Samanta, K. Venetsanou, P. Barbry, and S. Matalon Modification of biophysical properties of lung epithelial Na+ channels by dexamethasone Am J Physiol Cell Physiol, September 1, 2000; 279(3): C762 - C770. [Abstract] [Full Text] [PDF]

				A. Lazrak, A. Samanta, and S. Matalon Biophysical properties and molecular characterization of amiloride-sensitive sodium channels in A549 cells Am J Physiol Lung Cell Mol Physiol, April 1, 2000; 278(4): L848 - L857. [Abstract] [Full Text] [PDF]

				C. H. George, J. M. Kendall, A. K. Campbell, and W. H. Evans Connexin-Aequorin Chimerae Report Cytoplasmic Calcium Environments along Trafficking Pathways Leading to Gap Junction Biogenesis in Living COS-7 Cells J. Biol. Chem., November 6, 1998; 273(45): 29822 - 29829. [Abstract] [Full Text] [PDF]

				C. Peracchia, A. Sotkis, X. G. Wang, L. L. Peracchia, and A. Persechini Calmodulin Directly Gates Gap Junction Channels J. Biol. Chem., August 18, 2000; 275(34): 26220 - 26224. [Abstract] [Full Text] [PDF]