Voltage- and Ca2+-dependent burst generation in neuroendocrine dahlgren cells in the teleost platichthys flesus

Brierley, M. J., Bauer, C. S., Lu, W., Riccardi, Daniela ORCID: https://orcid.org/0000-0002-7322-3163, Balment, R. J. and McCrohan, C. R. 2004. Voltage- and Ca2+-dependent burst generation in neuroendocrine dahlgren cells in the teleost platichthys flesus. Journal of Neuroendocrinology 16 (10) , pp. 832-841. 10.1111/j.1365-2826.2004.01238.x

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Abstract

The neuroendocrine Type 1 Dahlgren cells of the caudal neurosecretory system of the flounder display characteristic bursting activity, which may increase secretion efficiency. The firing activity pattern in these cells was voltage-dependent; when progressively depolarized, cells moved from silent (approximately −70 mV), through bursting and phasic to tonic firing (< −65 mV). Brief (10 s) evoked bursts of spikes were followed by a slow after-depolarization (ADP; amplitude up to 10 mV, duration 10–200 s), which was also voltage-dependent and could trigger a prolonged burst. The ADP was significantly reduced in the absence of external Ca2+ ions or the presence of the L-type Ca2+ channel blocker, nifedipine. BayK 8644 (which increases L-type channel open times) significantly increased ADP duration, whereas the Ca2+-activated nonselective cation channel blocker, flufenamic acid, had no effect. Pharmacological blockade of Ca2+-activated K+ channels, using apamin and charybdotoxin, increased the duration of both ADP and evoked bursts. However, action potential waveform was unaffected by either apamin/charybdotoxin, nifedipine, BayK 8644 or removal of external Ca2+. The short duration (approximately 100 ms), hyperpolarization-activated, postspike depolarizing afterpotentials (DAP), were significantly reduced by nifedipine. We propose that long duration ADPs underlie bursts and that short duration DAPs play a role in modulation of spike frequency.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Biosciences
Publisher:	Wiley-Blackwell
ISSN:	0953-8194
Last Modified:	27 Oct 2022 08:49
URI:	https://orca.cardiff.ac.uk/id/eprint/63462

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