Porcine Müller glial cells increase expression of BKCa channels in retinal detachment.

Purpose: To determine whether experimental retinal detachment causes an alteration in Ca2 +-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).