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- Title
Differential expression of voltage-gated K<sup>+</sup> and Ca<sup>2+</sup> currents in bipolar cells in the zebrafish retinal slice.
- Authors
Connaughton; Maguire
- Abstract
Whole-cell voltage-gated currents were recorded from bipolar cells in the zebrafish retinal slice. Two physiological populations of bipolar cells were identified. In the first, depolarizing voltage steps elicited a rapidly activating A-current that reached peak amplitude ≤ 5 ms of step onset. I[sub A] was antagonized by external tetraethylammonium or 4-aminopyridine, and by intracellular caesium. The second population expressed a delayed rectifying potassium current (I[sub K]) that reached peak amplitude ≥ 10 ms after step onset and did not inactivate. I[sub K] was antagonized by internal caesium and external tetraethylammonium. Bipolar cells expressing I[sub K] also expressed a time-dependent h-current at membrane potentials < – 50 mV. I[sub h] was sensitive to external caesium and barium, and was also reduced by Na[sup +]-free Ringer. In both groups, a calcium current (I[sub Ca]) and a calcium-dependent potassium current (I[sub K(Ca)]) were identified. Depolarizing voltage steps > – 50 mV activated I[sub Ca], which reached peak amplitude between – 20 and – 10 mV. I[sub Ca] was eliminated in Ca[sup +2]-free Ringer and blocked by cadmium and cobalt, but not tetrodotoxin. In most cells, I[sub Ca] was transient, activating rapidly at – 50 mV. This current was antagonized by nickel. The remaining bipolar cells expressed a nifedipine-sensitive sustained current that activated between – 40 and – 30 mV, with both slower kinetics and smaller amplitude than transient I[sub Ca]. I[sub K(Ca)] was elicited by membrane depolarizations > – 20 mV. Bipolar cells in the zebrafish retinal slice preparation express an array of voltage-gated currents which contribute to non-linear I–V characteristics. The zebrafish retinal slice preparation is well-suited to patch clamp analyses of membrane mechanisms and provides a suitable model for studying genetic defects in visual system development.
- Publication
European Journal of Neuroscience, 1998, Vol 10, Issue 4, p1350
- ISSN
0953-816X
- Publication type
Academic Journal
- DOI
10.1046/j.1460-9568.1998.00152.x