L-type calcium channels in type I cells of the rat carotid body

Lynne A Fieber, E. W. McCleskey

Research output: Contribution to journalArticle

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Abstract

1. Whole-cell and cell-attached patch-clamp recordings were made from enzymatically isolated type I cells from the carotid body of adult rats. Voltage-dependent K+ and Ca2+ channels were observed, but there was no detectable Na+ current. In this respect, rat carotid body cells are unlike those from rabbit, which have Na+ currents and Na+-dependent action potentials. 2. The observed Ca2+ channels had the following properties: 1) activation requires voltage steps above -20 mV; 2) little inactivation occurred with holding voltages below -40 mV; 3) one single-channel conductance of 21 pS was found with 90 or 110 mM Ba2+ in the cell-attached pipette and this was the only conductance observed; 4) open probability was increased by the dihydropyridine Ca2+ channel agonist Bay K 8644 and was decreased by the antagonist nifedipine; and 5) ω-conotoxin had little or no effect on the channels. These are properties expected of L-type Ca2+ channels. 3. To investigate whether these voltage-dependent channels would be available for opening on membrane depolarization, we measured the type I cell resting membrane potential noninvasively using unitary openings of the L- type Ca2+ channel with Bay K 8644 in the cell-attached pipette. Resting potentials ranged from -62 to -13 mV, with a mean of -32 mV in 12 cells. 4. Judging from single-channel conductance and pharmacology, the Ca2+ current is mostly, if not solely, carried by L channels. Thus it should be possible to use modulators of L channel activity to determine the role of Ca2+ channels in stimulus-secretion coupling in the rat carotid body.

Original languageEnglish
Pages (from-to)1378-1384
Number of pages7
JournalJournal of Neurophysiology
Volume70
Issue number4
StatePublished - Nov 16 1993
Externally publishedYes

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Carotid Body
L-Type Calcium Channels
3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester
Membrane Potentials
Conotoxins
Nifedipine
Action Potentials
Cell Membrane
Pharmacology
Rabbits
Membranes

ASJC Scopus subject areas

  • Physiology
  • Neuroscience(all)

Cite this

L-type calcium channels in type I cells of the rat carotid body. / Fieber, Lynne A; McCleskey, E. W.

In: Journal of Neurophysiology, Vol. 70, No. 4, 16.11.1993, p. 1378-1384.

Research output: Contribution to journalArticle

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