Abstract
Membrane potential and resistance were measured from two neighbouring electrically coupled cells within the same mouse pancreatic acinus, using one electrode filled with KCl and another filled with K-EGTA [ethylene glycol-bis-(β-amino ethyl ether) N,N′-tetra acetic acid] or K-acetate. EGTA was injected into one cell by passing pulses of hyperpolarizing current through the EGTA microelectrode. In order to ensure constant membrane potential, pulses of depolarizing current of the same intensity were simultaneously passed through the other electrode.
Intracellular injection of EGTA, but not acetate, decreased significantly the membrane response (depolarization, resistance reduction) of both coupled cells to small microionophoretic pulses of ACh stimulation. Responses to larger doses were decreased to a smaller extent. Intracellular injection of EGTA also decreased significantly the membrane response of both coupled cells to microionophoretic pulses of pentagastrin stimulation.
In contrast intracellular injection of EGTA did not inhibit membrane response tol-alanine stimulation.l-Alanine-evoked membrane depolarization was independent of external Ca. This is in contrast to what has previously been shown for secretagogue effects.
It is concluded that EGTA-induced sequestration of cytosolic Ca2+ decreases membrane responses to both ACh and pentagastrin, providing new evidence of the crucial role played by internal Ca2+ in mediating stimulus-permeability coupling. In contrast,l-alanine action does not appear to be mediated by internal Ca2+.
Similar content being viewed by others
References
Brown JE, Coles JA, Pinto LH (1977) Effects of injections of calcium and EGTA into the outer segments of retinal rods of Bufo marinus. J Physiol (Lond) 269:707–722
Isenberg G (1977a) Cardiac Purkinje fibres. Resting, action, and pacemaker potential under the influence of [Ca2+]i as modified by intracellular injection techniques. Pflügers Arch 371:51–59
Isenberg G (1977b) Cardiac Purkinje fibres. The slow inward current component under the influence of modified [Ca2+]i. Pflügers Arch 371:61–69
Isenberg G (1977c) Cardiac Purkinje fibres. [Ca2+]i controls steady state potassium conductance. Pflügers Arch 371:71–76
Isenberg G (1977d) Cardiac Purkinje fibres. [Ca2+]i controls the potassium permeability via the conductance components gK1 and gK2. Pflügers Arch. 371:77–85
Iwatsuki N, Petersen OH (1977a) Acetylcholine-like effects of intracellular calcium application in pancreatic acinar cells. Nature 268:147–149
Iwatsuki N, Petersen OH (1977b) Pancreatic acinar cells: The acetylcholine equilibrium potential and its ionic dependency. J Physiol (Lond) 269:735–751
Iwatsuki N, Petersen OH (1978a) Electrical coupling and uncoupling of exocrine acinar cells. J Cell Biol 79:533–545
Iwatsuki N, Petersen OH (1978b) Intracellular Ca2+ injection causes membrane hyperpolarization and conductance increase in lacrimal acinar cells. Pflügers Arch 377:185–187
Iwatsuki N, Petersen OH (1979) Direct visualization of cell to cell coupling: Transfer of fluorescent probes in living mammalian pancreatic acini. Pflügers Arch 380:277–281
Iwatsuki N, Petersen OH (1980) Amino acids evoke short-lasting membrane conductance increase in pancreatic acinar cells. Nature 283:492–494
Laugier R, Petersen OH (1980) Pancreatic acinar cells: Electrophysiological evidence for stimulant-evoked increase in membrane calcium permeability. J Physiol (Lond) 303:61–72
Meech RS (1974) The sensitivity ofHelix aspersa neurons to injected calcium ions. J Physiol (Lond) 237:237–277
Nishiyama A, Petersen OH (1975) Pancreatic acinar cells: Ionic dependence of acetylcholine-induced membrane potential and resistance change. J Physiol (Lond) 244:431–465
Petersen OH (1976) Electrophysiology of mammalian gland cells. Physiol Rev 56:535–577
Petersen OH (1980) Electrophysiology of gland cells. Academic Press, London, New York
Petersen OH, Iwatsuki N (1978) The role of calcium in pancreatic acinar cell stimulus-secretion coupling: An electrophysiological approach. Ann NY Acad Sci 307:599–617
Petersen OH, Philpott HG (1979) Pancreatic acinar cells: Effects of microionophoretic polypeptide application on membrane potential and resistance. J Physiol (Lond) 290:305–315
Petersen OH, Ueda N (1976) Pancreatic acinar cells. The role of calcium in stimulus-secretion coupling. J Physiol (Lond) 254: 583–606
Philpott HG, Petersen OH (1979) Separate activation sites for cholecystokinin and bombesin on pancreatic acini. An electrophysiological study employing a competitive antagonist for the action of CCK. Pflügers Arch 382:263–267
Putney JW Jr (1979) Stimulus-permeability coupling: Role of calcium in the receptor regulation of membrane permeability. Pharmacol Rev 30:209–245
Schulz I, Heil K (1979) Ca2+ control of electrolyte permeability in plasma membrane vesicles from cat pancreas. J Membr Biol 46: 41–70
Schulz I, Ullrich KJ (1979) Transport processes in the exocrine pancreas. In: Giebisch G, Tosteson DJ, Ussing HH (eds) Membrane transport in biology, Vol IV. Springer, Berlin, Heidelberg, New York
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Laugier, R., Petersen, O.H. Effects of intracellular EGTA injection on stimulant-evoked membrane potential and resistance changes in pancreatic acinar cells. Pflugers Arch. 386, 147–152 (1980). https://doi.org/10.1007/BF00584202
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00584202