Porcine Müller Glial Cells Increase Expression of BK_Ca Channels in Retinal Detachment

Abstract

Purpose: To determine whether experimental retinal detachment causes an alteration in Ca^{2 +}-activated, big conductance K⁺ (BK) currents of Müller glial cells. Methods: Rhegmatogenous retinal detachment was induced in porcine eyes. Müller cells were acutely isolated from control retinas and from retinas that were detached for 7 days. BK currents were detected by using the BK channel opener and the blocker phloretin and tetraethylammonium, respectively. Results: In addition to cellular hypertrophy and a decrease in inward rectifier K⁺ currents, Müller cells from detached retinas showed an increase in the amplitude of currents mediated by BK channels (850 ± 105 pA) when compared with cells from control retinas (228 ± 60 pA; p < 0.001). Similarly, the density of the BK channel–mediated currents was greater in cells from detached retinas (12.32 ± 1.52 pA/pF) compared with control cells (4.07 ± 1.07 pA/pF; p < 0.001). The increase in BK currents was correlated with the decrease of the inward rectifier K⁺ currents. Conclusions: It is suggested that an increase in the expression of functional BK channels may be involved in gliotic responses of Müller cells after retinal detachment (e.g., in mitogen-induced Ca²⁺ responses and cellular proliferation).

KEYWORDS:

• Müller cells
• pig
• potassium channels
• retinal detachment