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Ionic currents in dispersed chemoreceptor cells of the mammalian carotid body
dc.creator | Ureña López, Juan | |
dc.creator | López López, J. | |
dc.creator | González Montelongo, M. Carmen | |
dc.creator | López Barneo, José | |
dc.date.accessioned | 2015-01-14T13:52:29Z | |
dc.date.available | 2015-01-14T13:52:29Z | |
dc.date.issued | 1989 | |
dc.identifier.issn | 1540-7748 | es |
dc.identifier.issn | 0022-1295 | es |
dc.identifier.uri | http://hdl.handle.net/11441/17477 | |
dc.description.abstract | Ionic currents of enzymatically dispersed type I and type II cells of the carotid body have been studied using the whole cell variant of the patch-clamp technique. Type II cells only have a tiny, slowly activating outward potassium current. By contrast, in every type I chemoreceptor cell studied we found (a) sodium, (b) calcium, and (c) potassium currents. (a) The sodium current has a fast activation time course and an activation threshold at approximately -40 mV. At all voltages inactivation follows a single exponential time course. The time constant of inactivation is 0.67 ms at 0 mV. Half steady state inactivation occurs at a membrane potential of approximately -50 mV. (b) The calcium current is almost totally abolished when most of the external calcium is replaced by magnesium. The activation threshold of this current is at approximately -40 mV and at 0 mV it reaches a peak amplitude in 6-8 ms. The calcium current inactivates very slowly and only decreases to 27% of the maximal value at the end of 300-ms pulses to 40 mV. The calcium current was about two times larger when barium ions were used as charge carriers instead of calcium ions. Barium ions also shifted 15-20 mV toward negative voltages the conductance vs. voltage curve. Deactivation kinetics of the calcium current follows a biphasic time course well fitted by the sum of two exponentials. At -80 mV the slow component has a time constant of 1.3 +/- 0.4 ms whereas the fast component, with an amplitude about 20 times larger than the slow component, has a time constant of 0.16 +/- 0.03 ms. These results suggest that type I cells have predominantly fast deactivating calcium channels. The slow component of the tails may represent the activity of a small population of slowly deactivating calcium channels, although other possibilities are considered. (c) Potassium current seems to be mainly due to the activity of voltage-dependent potassium channels, but a small percentage of calcium-activated channels may also exist. This current activates slowly, reaches a peak amplitude in 5-10 ms, and thereafter slowly inactivates. Inactivation is almost complete in 250-300 ms. The potassium current is reversibly blocked by tetraethylammonium. Under current-clamp conditions type I cells can spontaneously fire large action potentials. These results indicate that type I cells are excitable and have a variety of ionic conductances. We suggest a possible participation of these conductances in chemoreception. | es |
dc.language.iso | eng | es |
dc.relation.ispartof | The Journal of general physiology, 93 (5), 979-999. | es |
dc.rights | Atribución-NoComercial-SinDerivadas 4.0 España | * |
dc.rights.uri | http://creativecommons.org/licenses/by-nc-nd/4.0/ | * |
dc.title | Ionic currents in dispersed chemoreceptor cells of the mammalian carotid body | es |
dc.type | info:eu-repo/semantics/article | es |
dc.rights.accessRights | info:eu-repo/semantics/openAccess | es |
dc.contributor.affiliation | Universidad de Sevilla. Departamento de Fisiología Médica y Biofísica | es |
dc.journaltitle | The Journal of general physiology | es |
dc.publication.volumen | 93 | es |
dc.publication.issue | 5 | es |
dc.publication.initialPage | 979 | es |
dc.publication.endPage | 999 | es |
dc.identifier.idus | https://idus.us.es/xmlui/handle/11441/17477 |
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