Electrical and Secretory Response to Cholinergic Stimulation in Mouse and Human Adrenal Medullary Chromaffin Cells
Chromaffin cells from the adrenal gland secrete catecholamines in response to acetylcholine (ACh).(1,2) ACh induces a transient depolarization of the adrenal chromaffin cell membrane, which in some animals is due to the opening of nicotinic-receptor channels.(3–7) It has been observed that the ACh-induced depolarization is often accompanied by the generation of action potentials or by a marked increase in the frequency of spontaneously occuring action potentials.(3,6–9) These action potentials are presumably due to the activation of both Na+ and Ca2+ voltage-gated ionic channels. Blocking Na + -channels with tetrodotoxin (TTX) leads to a partial inhibition of the stimulated release of catecholamines.(10,11) This result suggests that Ca2+ entry associated with the ACh-evoked depolarization is reduced in the presence of TTX.(10,11) The rapid depolarization resulting from the activation of Na+ -channels should enhance Ca2+ entry by recruitment of Ca2+ -channels with a more positive potential for activation. This is presumably the physiological pathway for Ca2+ entry at low concentrations of ACh (10 μM). At high concentrations of ACh (55 μM), however, additional Ca2+ entry occurs through the ACh nicotinic-receptor channel.(12) While Ca2+ entry through the ACh-channel is restricted to the small region of clustered nicotinic-receptor channels, voltage-dependent Ca2+ -channels are probably evenly distributed over the entire cell surface as patch-clamp(9) and other studies(13) appear to indicate.
KeywordsCurrent Pulse Chromaffin Cell Adrenal Medulla Rest Membrane Potential Input Resistance
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- 13.Kidokoro, Y., 1985, Electrophysiology of adrenal chromaffin cell, in: The Electrophysiology of the Secretory Cell (A. M. Poisner and J. M. Trifaro, eds.), Elsevier, Amsterdam, pp. 195–218.Google Scholar
- 14.Nassar-Gentina, V., Pollard, H. B., and Rojas, E., 1988, Electrical activity in chromaffin cells of intact mouse adrenal gland, Am. J. Physiol. 254: 675–683.Google Scholar
- 20.Ferrer, R., Soria, B., Dawson, C. M., Atwater, I., and Rojas, E., 1984, Effects of Zn on glucose-induced electrical activity and insulin release from mouse pancreatic islets, Am. J. Physiol. 246: C5–C527.Google Scholar
- 23.Oka, M., Isosaki, M., and Watanabe, J., 1980, Calcium flux and catecholamine release in isolated bovine adrenal medullary cells: Effects of nicotinic and muscarinic stimulation, in: Synthesis, Storage and Secretion of Adrenal Catecholamines, Advances in the Biosciences, Vol. 36, pp. 29–36.Google Scholar
- 27.Friedman, J. E., Lelkes, P. I., Lavie, E., Rosenheck, K., Schneeweiss, F., and Schneider, A. S., 1985, Membrane potential and catecholamine secretion by bovine adrenal chromaffin cells: Use of tetraphenylphosphorium distribution and carbocyanine dye fluorescence, J. Neurochem. 44: 1391–1402.PubMedCrossRefGoogle Scholar
- 35.Lee, F. L., and Trendelenburg, U., 1967, Muscarinic transmission of preganglionic impulses to the adrenal medulla of the cat, J. Pharmacol. Exp. Therap. 158: 73–79.Google Scholar