title: Slow depolarizing afterpotentials in neocortical neurons are sodium and calcium dependent.
abstract: Depolarizing afterpotentials (DAPs) were studied in intracellular recordings from neocortical slices bathed in tetrodotoxin (TTX) (1 microM) and tetraethylammonium chloride (TEA) (24 mM), to block voltage-dependent Na+ currents and most K+ currents. The DAP was Ca(2+)-dependent, in that its magnitude varied as a function of the duration of the preceding Ca2+ plateau. It had an apparent reversal potential of between -40 and -5 mV. The DAP was blocked when choline replaced all extracellular Na+; there was a hyperpolarizing shift in apparent reversal potential when extracellular Na+ was lowered. The DAP was blocked by amiloride (1 mM), which also decreased the preceding Ca2+ plateau. The data are consistent with the hypothesis that the DAP is due to electrogenic Na+/Ca2+ exchange.
authors.affiliation: Department of Physiology, Corob Center for Medical Research, Faculty of Health Sciences, Ben Gurion University of the Negev, Beersheva, Israel.
authors.forename: A
authors.initials: A
authors.lastname: Friedman
authors.forename: J
authors.initials: J
authors.lastname: Arens
authors.forename: U
authors.initials: U
authors.lastname: Heinemann
authors.forename: M J
authors.initials: MJ
authors.lastname: Gutnick
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology*; D002794:Choline / Q000494:pharmacology; D004558:Electric Stimulation; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D012964:Sodium / Q000378:metabolism / Q000494:pharmacology*; D013003:Somatosensory Cortex / Q000502:physiology*; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D013757:Tetraethylammonium Compounds; D013779:Tetrodotoxin; D019789:Tetraethylammonium; D012964:Sodium; D002794:Choline; D002118:Calcium