High-voltage-activated calcium channels in Mueller cells acutely isolated from tiger salamander retina

Mueller cells mediate retinal function by stabilizing the ionic environment and signal glial network activity via calcium waves. Using whole-cell patch clamp recording, we describe a high-voltage-activated, slowly inactivating Ca channel current in isolated salamander Mueller cells that has unusual pharmacological properties. The Ca channel current has an activation midpoint of [sim]-8 mV and an inactivation midpoint of [sim]-26 mV in 10 mM Ba super(2+). The time constant for inactivation is [sim]380 ms at potentials positive to zero. The current is blocked by Cd super(2+) with an EC sub(50) of