Differential expression of voltage‐gated K⁺ and Ca²⁺ currents in bipolar cells in the zebrafish retinal slice

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 < or = 5 ms of step onset. IA was antagonized by external tetraethylammonium or 4-aminopyridine, and by intracellular caesium. The second population expressed a delayed rectifying potassium current (IK) that reached peak amplitude > or = 10 ms after step onset and did not inactivate. IK was antagonized by internal caesium and external tetraethylammonium. Bipolar cells expressing IK also expressed a time-dependent h-current at membrane potentials < -50 mV. Ih was sensitive to external caesium and barium, and was also reduced by Na+-free Ringer. In both groups, a calcium current (ICa) and a calcium-dependent potassium current (IK(Ca)) were identified. Depolarizing voltage steps > -50 mV activated ICa, which reached peak amplitude between -20 and -10 mV. ICa was eliminated in Ca+2-free Ringer and blocked by cadmium and cobalt, but not tetrodotoxin. In most cells, Ica 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 ICa. IK(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.

Mercury-induced epigenetic transgenerational inheritance of abnormal neurobehavior is correlated with sperm epimutations in zebrafish

“…Fish were then removed from the tricaine, decapitated, and the eyes were removed. Retinal slices were prepared following established protocols [31–33]. Whole-cell voltage-gated current responses were then recorded from bipolar cells within intact zebrafish retinal slice preparations using methods described previously [12].…”

Roles of ON Cone Bipolar Cell Subtypes in Temporal Coding in the Mouse Retina

“…Because we isolated the transmission between photoreceptors and ON bipolar cells, the response diversity most likely occurs by signal modulation within ON bipolar cells. Heterogeneous expression of voltage-gated channels has been reported (Connaughton and Maguire, 1998;Pan and Hu, 2000;Pan, 2000;Ichinose et al, 2005;Cangiano et al, 2007) and might contribute to subtype-dependent temporal tuning in ON bipolar cells.…”

“…7), voltage-gated channels might play a key role. For example, HCN channels suppressed lower-frequency responses to shape bandpass filtering in rod bipolar cells (Cangiano et al, 2007). HCN channels are expressed in cone bipolar cells Puthussery et al, 2013) and might contribute to shaping sustained responses in some bipolar cells.…”

Neural circuitry and plasticity in the adult vertebrate inner retina

“…Retinal slices arc made according to the procedures described by [6] as adapted from [I 0]. The physiologically recorded cells are also identified using either Lucifer yellow or Calccin dyes to fill the cell which is then made to nuoresce under appropriate illuminating conditions.…”

“…In tiger salamander retina, the presynaptic bipolar cells appear to only usc sustain.ed type voltage-gated calcium channels [5] that would support sustained calcium-dependent glutamate release. But in fish retina, the presynaptic bipolar cells come in two types with respect to voltage-gated calcium channels; one type expressing only sustained and the other type expressing only transient voltage-gated calcium channels [6], and thus calcium-dependent glutamate release could he brief at those synapses where the bipolar cell expresses transient calcium current, or prolonged where the bipolar cell expresses sustained calcium current.…”