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Muscarinic receptors regulate two different calcium‐dependent non‐selective cation currents in rat prefrontal cortex
Author(s) -
HajDahmane Samir,
Andrade Rodrigo
Publication year - 1999
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1046/j.1460-9568.1999.00612.x
Subject(s) - carbachol , chemistry , biophysics , hyperpolarization (physics) , pyramidal cell , membrane potential , muscarinic acetylcholine receptor , calcium , time constant , hcn channel , neuroscience , receptor , ion channel , biochemistry , biology , stereochemistry , hippocampal formation , organic chemistry , nuclear magnetic resonance spectroscopy , electrical engineering , engineering
Pyramidal neurons of layer V in rat prefrontal cortex display a prominent fast afterdepolarization (fADP) and a muscarinic‐induced slow afterdepolarization (sADP). We have shown previously that both of these ADPs are produced by the activation of calcium‐dependent non‐selective cation currents. In the present report we examine whether they represent two distinct currents. In most pyramidal neurons recorded with caesium gluconate‐based intracellular solution, a calcium spike is followed by a fast decaying inward aftercurrent (I fADP ). The decay of I fADP is monoexponential with a time constant (τ) of ≈ 35 ms. Administration of carbachol (10–30 μm) increases the time constant of this decay by ≈ 80% and induces the appearance of a much slower inward aftercurrent (I sADP ). I fADP recorded in control conditions and in the presence of carbachol increases linearly with membrane hyperpolarization. In contrast, the carbachol‐induced I sADP decreases with membrane hyperpolarization. When the sodium driving force across the cell membrane was reduced, I fADP was found to reverse at around −40 mV whereas I sADP remain inward over the same voltage range tested. Finally, bath administration of flufenamic acid (100 μm–1 mm) selectively blocks the carbachol‐induced I sADP without a significant effect on the amplitude of I fADP . These differences in the electrical and pharmacological properties of I fADP and I sADP suggest that they were mediated by two distinct non‐selective cation currents.