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Cellular basis of transduction in carotid chemoreceptors

Biscoe, TJ; Duchen, MR; (1990) Cellular basis of transduction in carotid chemoreceptors. American Journal of Physiology - Lung Cellular and Molecular Physiology , 258 (6 2-3)

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Abstract

Understanding transduction mechanisms is central to much of sensory physiology. The carotid chemoreceptors monitor the PO2 of arterial blood en route to the brain and are powerfully excited when the arterial PO2 falls to < 60 mmHg. The type I cell is generally believed to be the transducer. These cells release catecholamines in response to agents that excite the receptor (hypoxia, cyanide, K+-induced depolarization, etc.). Adherent to the cells are the saucer-shaped nerve endings of the axons of the sinus nerve. We and others have used patch-clamp techniques to study the electrophysiological properties of the type I cells. We have also investigated type I cell chemistry with microfluorometric techniques, to measure intracellular Ca2+ concentration ([Ca2+](i)), mitochondrial NADH, and mitochondrial membrane potential (ΔΨ(m)). During hypoxia there are graded increases in NADH, [Ca2+](i) (which presumably will promote transmitter release), and graded depolarization of ΔΨ(m). These results suggest that the Ca2+ is largely derived from an intracellular store, probably from mitochondria, and that release is entrained to ΔΨ(m). Comparative studies with other cells indicate an increased sensitivity of the mitochondria of type I cells to changes in PO2. The data suggest that the electrophysiological responses of type I cells to hypoxia are not central to the response, although the excitability of the cells may provide a mechanism for the modulation of the response by varying voltage-gated Ca2+ influx.

Type: Article
Title: Cellular basis of transduction in carotid chemoreceptors
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences > Cell and Developmental Biology
URI: http://discovery.ucl.ac.uk/id/eprint/1497828
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