title: Different contributions of calcium channel subtypes to electrical excitability of chromaffin cells in rat adrenal slices.
abstract: We characterized the ionic currents underlying the cellular excitability and the Ca(2+) -channel subtypes involved in action potential (AP) firing of rat adrenal chromaffin cells (RCCs) preserved in their natural environment, the adrenal gland slices, through the perforated patch-clamp recording technique. RCCs prepared from adrenal slices exhibit a resting potential of -54 mV, firing spontaneous APs (2-3 spikes/s) generated by the opening of Na(+) and Ca(2+) -channels, and terminated by the activation of voltage and Ca(2+) -activated K(+) -channels (BK). Ca(2+) influx via L-type Ca(2+) -channels is involved in reaching threshold potential for AP firing, and is responsible for activation of BK-channels contributing to AP-repolarization and afterhyperpolarization, whereas P/Q-type Ca(2+) -channels are involved only in the repolarization phase. BK-channels carry total outward current during AP-repolarization. Blockade of L-type Ca(2+) -channels reduces BK-current ~60%, whereas blockade of N- or P/Q-type produces little effect. This study demonstrates that Ca(2+) influx through L-type Ca(2+) -channels plays a key role in modulating the threshold potential from RCCs in situ. This study demonstrates that Ca(2+) influx through L-type Ca(2+) channels plays a key role in modulating the threshold potential for action potential firing and activating BK channels contributing to repolarization and afterhyperpolarization from rat adrenal chromaffin cells in situ.
authors: Departament of Pharmacology and Therapeutics, University Autónoma de Madrid, Madrid, Spain; Instituto Teófilo Hernando, University Autónoma de Madrid, Madrid, Spain; Facultad de Medicina, University Autónoma de Madrid, Madrid, Spain.
authors: Elisa
authors: E
authors: Albiñana
authors: Pedro
authors: P
authors: Segura-Chama
authors: Andres M
authors: AM
authors: Baraibar
authors: Arturo
authors: A
authors: Hernández-Cruz
authors: Jesus M
authors: JM
authors: Hernández-Guijo
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000311:Adrenal Glands / Q000166:cytology*; D000818:Animals; D055592:Biophysical Phenomena / Q000187:drug effects; D001703:Biophysics; D019256:Cadmium Chloride / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology*; D019439:Chromaffin Cells / Q000187:drug effects / Q000502:physiology*; D004558:Electric Stimulation; D066298:In Vitro Techniques; D008297:Male; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D026941:Sodium Channel Blockers / Q000494:pharmacology; D019789:Tetraethylammonium / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D002121:Calcium Channel Blockers; D015220:Calcium Channels; D026902:Potassium Channel Blockers; D026941:Sodium Channel Blockers; D013779:Tetrodotoxin; D019789:Tetraethylammonium; D019256:Cadmium Chloride; D002118:Calcium
keywords: action potentials; adrenal slices; calcium channels; rat chromaffin cell