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Effects of Putative Neurotransmitters of the Carotid Body on its Own Glomus Cells
Author(s) -
Eyzaguirre C.,
MontiBloch L.,
Woodbury J. W.
Publication year - 1990
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 - 10.1111/j.1460-9568.1990.tb00383.x
Subject(s) - glomus cell , carotid body , depolarization , acetylcholine , substance p , endocrinology , medicine , receptor , membrane potential , chemistry , biology , neuropeptide , acetylcholine receptor , microbiology and biotechnology , biophysics , stimulation
Carotid body glomus cells produce and release acetylcholine (ACh), catecholamines, and neuropeptides, and there is biochemical evidence that these cells possess receptors for these substances. Thus, we studied the effects of cholinergics [ACh, nicotine (Nic), bethanechol (BN)] and peptides [met‐enkephalin (ME), substance P (SP)] on the membrane potential (E m ), voltage noise (E rms ), and input resistance (R 0 ) of glomus cells. Sliced carotid bodies (for cell visualization) of cats, rabbits, and mice were used. The mean E m and R 0 of rabbit glomus cells were lower than those of cat and mouse. R 0 of mouse cells was the largest, whereas E rms was similar in all species. The various agents had qualitatively similar effects on the cells of the three species although some quantitative differences were sometimes observed. But, for simplicity, results were pooled. ACh depolarized most cells (effect depressed by zero [Ca 2+ ] 0 and Mn 2+ ), reduced their resistance, and induced variable changes in E rms . Different ACh doses produced non‐linear effects on ΔE m . Nic and BN also depolarized most cells, reducing R 0 and E rms . Atropine depressed the cell responses to BN; α‐bungarotoxin the depolarizing response to Nic. ME and SP depolarized most cells, but only ME significantly reduced R 0 . Neither peptide significantly changed voltage noise. Comparing the effects of all drugs showed that BN was the most effective depolarizing agent, producing the largest reductions in R 0 . There were negative correlations between ΔE m and ΔR 0 with the cholinergics and SP; correlations between ΔE rms and ΔR 0 were significant and positive only with the cholinergics. These results confirm the presence of nicotinic, muscarinic, and peptidergic receptors in glomus cells. The similar effects of cholinergics and peptides and those of flow interruption and anoxia suggest that the latter may partly act via autoreceptors for the released transmitters.