| Autor: |
Masetto, Sergio, Zampini, Valeria, Zucca, Giampiero, Valli, Paolo |
| Předmět: |
|
| Zdroj: |
Pflügers Archiv: European Journal of Physiology; Nov2005, Vol. 451 Issue 2, p395-408, 14p, 1 Diagram, 1 Chart, 22 Graphs |
| Abstrakt: |
Type I and Type II hair cells, and Type II hair cells located in different zones of the semicircular canal crista, express different patterns of voltage-dependent K channels, each one specifically shaping the hair cell receptor potential. We report here that, close to hatching, chicken embryo semicircular canal Type I and Type II hair cells express a similar voltage-dependent L-type calcium current ( I Ca), whose main features are: activation above −60 mV, fast activation kinetics, and scarce inactivation. I Ca should be already active at rest in Zone 1 Type II hair cells, whose resting membrane potential was on average slightly less negative than −60 mV. Conversely, I Ca would not be active at rest in Type II hair cells from Zone 2 and 3, nor in Type I hair cells, since their resting membrane potential was significantly more negative than −60 mV. However, even small depolarising currents would activate I Ca steadily in Zone 2 and 3 Type II hair cells, but not in Type I hair cells because of the robust repolarising action of their specific array of K+ currents. The implications of the present findings in the afferent discharge are discussed. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
|
Full text from SpringerLink