Electrical activity in chromaffin cells of intact mouse adrenal gland.
Membrane potentials of medullary chromaffin cells of the adrenal gland of the mouse were measured in situ. Resting potential (-54.3 +/- 8.8 mV) depended on extracellular [K+] as predicted by the constant-field equation with a permeability ratio, PNa/PK, of 0.09. Current-voltage (I-V) relationships showed that the current is rectified across the chromaffin cell membrane. A rectification ratio of 0.4 was calculated from the slopes of the I-V curves for positive (41 +/- 26 M omega) and negative (103 +/- M omega) currents. Because input resistance for a resting chromaffin cell in isolation is approximately 5 G omega, the chromaffin cells in situ behave as if they were electrically coupled. Most cells responded to depolarizing current pulses with repetitive action potentials, but only 50% of them showed spontaneous electrical activity. Spontaneous activity was often seen in the presence of tetrodotoxin (3 microM). Although the application of the K+-channel blockers tetraethylammonium and Ba2+ greatly increased the amplitude of the action potentials, only Ba2+ induced continuous electrical activity. Application of acetylcholine (ACh) always depolarized the cell membrane. This effect was blocked by atropine but not by D-tubocurarine, suggesting that ACh stimulation of chromaffin cells in the mouse involves activation of muscarinic receptors.
Nassar-Gentina
V
V
Laboratory of Cell Biology and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda 20892.
Pollard
H B
HB
Rojas
E
E
D000109:Acetylcholine / Q000494:pharmacology; D000311:Adrenal Glands / Q000502:physiology* / Q000648:ultrastructure; D000465:Algorithms; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001464:Barium / Q000378:metabolism; D002837:Chromaffin Granules / Q000502:physiology*; D002838:Chromaffin System / Q000502:physiology*; D004594:Electrophysiology; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D011188:Potassium / Q000378:metabolism; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D014403:Tubocurarine / Q000494:pharmacology
D013757:Tetraethylammonium Compounds; D001464:Barium; D001285:Atropine; D000109:Acetylcholine; D011188:Potassium; D014403:Tubocurarine