title: Origin of the after-hyperpolarization that follows removal of depolarizing agents from the isolated superior cervical ganglion of the rat.
abstract: 1. Potential changes in isolated rat superior cervical ganglia following addition and removal of depolarizing agents were recorded using a moving-fluid extracellular electrode system.2. Ganglionic negativity produced by carbachol was followed by a pronounced ganglionic positivity on washing. This after-positivity was attributed to hyperpolarization of the ganglion cells since it was unaffected by crushing the postganglionic trunk.3. The after-hyperpolarization was selectively depressed by (a) cooling (Q(10) 2.3), (b) metabolic inhibitors (cyanide, azide, 2,4-dinitrophenol), (c) reducing [K(+)](o) or substituting Cs(+) for K(+), (d) ouabain, and (e) substituting Li(+) for Na(+). This suggested a close dependence on active Na(+) transport.4. When K(+) was restored to K(+)-free solution, or the preparation was warmed rapidly, or when metabolic inhibitors were washed away, the hyperpolarization was rapidly regenerated. The effect of restoring K(+) indicated that the hyperpolarization was generated directly by the Na(+) pump.5. The hyperpolarization was not altered by replacing Cl(-) with isethionate, indicating that the voltage change produced by the Na(+) current was not modified by passive Cl(-) movements.6. Hexamethonium added to the washout fluid augmented the after-hyperpolarization, suggesting that there was a high (cationic) leak current due to continued receptor-activation on washing with normal Krebs solution.7. The hyperpolarization was reduced by omission of Ca(2+) and restored by addition of Mg(2+). This was considered to result from changes in passive membrane permeability.8. The time-course of post-carbachol hyperpolarization accorded with a Na(+) extrusion process whose rate was directly proportional to [Na(+)](i) with a rate constant of 0.38+/-0.02 min(-1) at 23-27 degrees C.9. With increasing concentrations of carbachol, the amplitude of the hyperpolarization increased in proportion to the preceding depolarization, but the rate constant of the hyperpolarization was unchanged.
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001386:Azides / Q000494:pharmacology; D001693:Biological Transport, Active; D002118:Calcium / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology*; D002463:Cell Membrane Permeability / Q000187:drug effects; D002586:Cesium / Q000494:pharmacology; D002712:Chlorides / Q000494:pharmacology; D003080:Cold Temperature; D003486:Cyanides / Q000494:pharmacology; D004140:Dinitrophenols / Q000494:pharmacology; D004492:Edetic Acid / Q000494:pharmacology; D004594:Electrophysiology; D005725:Ganglia, Autonomic / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D008094:Lithium / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D012964:Sodium / Q000378:metabolism / Q000494:pharmacology; D013451:Sulfonic Acids / Q000494:pharmacology
chemical_list: D001386:Azides; D002712:Chlorides; D003486:Cyanides; D004140:Dinitrophenols; D013451:Sulfonic Acids; D002586:Cesium; D010042:Ouabain; D002217:Carbachol; D008094:Lithium; D004492:Edetic Acid; D012964:Sodium; D008274:Magnesium; D000109:Acetylcholine; D011188:Potassium; D002118:Calcium