| Title | MAXIK POTASSIUM CHANNELS IN THE FUNCTION OF CHEMORECEPTOR CELLS OF THE RAT CAROTID BODY. | | Author(s) | Gomez-Niño A, Obeso A, Baranda JA, Santo-Domingo J, Lopez-Lopez JR, Gonzalez C | | Institution | University of Valladolid. | | Source | Am J Physiol Cell Physiol 2009 Jul 1. | | Abstract | Hypoxia activates chemoreceptor cells of the carotid body (CB) promoting an increase in their normoxic release of neurotransmitters. Catecholamine (CA) release rate parallels the intensity of hypoxia. Coupling of hypoxia to CA release requires cell depolarization, produced by inhibition of O2-regulated K(+) channels, and Ca(2+) entering the cells via voltage-operated channels. In rat chemoreceptor cells hypoxia inhibits maxiK and a TASK-like channel, but the significance of maxiK is controversial. A proposal envisions maxiK contributing to set the membrane potential (Em) and the hypoxic response, but the proposal is denied by authors finding that maxiK inhibition does not depolarize chemoreceptor cells or alters [Ca(2+)]i or CA release in normoxia or hypoxia. We found that maxiK channel blockers (tetraethylammonium and iberiotoxin) did not modify CA release in rat chemoreceptor cells, either in normoxia or hypoxia, and iberiotoxin did not alter the Ca(2+) transients elicited by hypoxia. On the contrary, both maxiK blockers increased the responses elicited by dinitrophenol, a stimulus we demonstrate does not affect maxiK channels in isolated patches of rat chemoreceptor cells. We conclude that in rat chemoreceptor cells maxiK channels do not contribute to the genesis of the Em, and that their full inhibition by hypoxia, preclude further inhibition by maxiK channel blockers. We suggest that full inhibition of this channel is required to generate the spiking behaviour of the cells in acute hypoxia. Key words: Hypoxia, catecholamine, iberiotoxin, intracellular calcium. | | Language | ENG | | Pub Type(s) | JOURNAL ARTICLE
| | PubMed ID | 19570892 |
|
