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Nicotinic and muscarinic reactive sites in mammalian glomus cells

C Eyzaguirre, L Monti-Bloch

    Brain Research
    |December 2, 1982
    PubMed

    Insights

    Nicotinic and muscarinic receptors on carotid body glomus cells were identified. These receptors influence cell depolarization and input resistance, suggesting roles in sensory transduction.

    Area of Science:

    • Neuroscience
    • Cell Biology
    • Physiology

    Background:

    • The carotid body acts as a peripheral chemoreceptor, sensing blood oxygen and carbon dioxide levels.
    • Glomus cells within the carotid body are crucial for this sensory function.
    • Understanding the receptors on glomus cells is key to elucidating carotid body physiology.

    Purpose of the Study:

    • To identify and characterize nicotinic and muscarinic receptor sites on carotid body glomus cells.
    • To investigate the electrophysiological effects of activating these receptors on glomus cell membrane potential and resistance.
    • To determine the involvement of specific receptor subtypes in modulating glomus cell responses.

    Main Methods:

    • Electrophysiological recordings (whole-cell patch-clamp) were performed on carotid body slices from cats, rabbits, and mice.
    • Cells were impaled under Nomarski differential interference contrast microscopy.
    • Nicotinic agonists (nicotine) and muscarinic agonists (pilocarpine, bethanechol) were applied, along with antagonists (curare, alpha-bungarotoxin, atropine).

    Main Results:

    • Nicotine, pilocarpine, and bethanechol induced depolarization of glomus cells, accompanied by a decrease in input resistance.
    • The effects of nicotine were significantly reduced by curare and alpha-bungarotoxin, indicating nicotinic receptor involvement.
    • Atropine similarly attenuated the responses to pilocarpine and bethanechol, suggesting muscarinic receptor activation.

    Conclusions:

    • Carotid body glomus cells possess both functional nicotinic and muscarinic receptors.
    • Activation of these receptors leads to significant changes in glomus cell membrane potential and input resistance.
    • These findings highlight the complex neurotransmitter/neuromodulator systems influencing carotid body chemoreception.

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