Whole-Cell Patch Clamping of Isolated Fiber Cells Confirms that Spatially Distinct Cl⁻Influx and Efflux Pathways Exist in the Cortex of the Rat Lens

Abstract

In peripheral cells, Cl(-) efflux is primarily mediated by potassium chloride cotransporters (KCCs) and its activity can be upregulated by hyposmotic challenge. In addition, these cells also contain a Cl(-) channel that exhibits a variable baseline activity level and that can be recruited to effect regulatory volume decrease if the KCC transporters are inhibited.

Identification of a nonselective cation channel in isolated lens fiber cells that is activated by cell shrinkage

“…In the present study, fiber cells exposed to hypertonic stress exhibited a transient upregulation of the La 3ϩ -sensitive NSC conductance, which appeared to preserve cell volume (Fig. 7B) presumably due to the parallel presence of anion transport pathways in lens fiber cells (6,41). Unfortunately, because of the elongated nature of the fiber cells, it proved impossible by differential interference contrast microscopy to quantify transient changes in fiber cell volume and morphology associated with activation of the NSC conductance that occur during RVI.…”

Eph-ephrin Signaling Affects Eye Lens Fiber Cell Intracellular Voltage and Membrane Conductance

“…If loss of EphA2 induces an increase in surface cell membrane K + -conductance, the effect on intracellular voltage would not be large since surface cell voltage is already close to E K . Another possibility is the increase in surface cell membrane Cl −conductance (Mathias et al, 1997(Mathias et al, , 2007Webb and Donaldson, 2009), which would also not significantly affect intracellular voltage since intracellular chloride is close to transmembrane equilibrium. Perhaps our methodology is not sensitive enough to detect the small voltage hyperpolarization in lenses from 12-month-old EphA2 −/− mice.…”