Low-Voltage-Activated Calcium Channels
Low-voltage-activated (LVA) calcium channels are a class of voltage-gated calcium (Ca2+) channels that exhibit a high probability of opening at hyperpolarized membrane voltages (negative to −50 mV). LVA channels consist of a Cav3 family, of which there are three isoforms (Cav3.1 (α1G), 3.2 (α1H), 3.3 (α1I)). Cav3 channels exhibit a low single-channel conductance and rapid inactivation, resulting in “tiny” and “transient” currents, often termed T-type current or IT. T-type calcium channels were first recognized for their contribution to burst depolarizations and pacemaker activity in specific neurons but are now known to influence a wide range of cell outputs (Huguenard 1996; Perez-Reyes 2003; Yunker and McEnery 2003).
Several families of Ca2+ channels are expressed in neurons, which can be broadly classified in two groups based on voltage dependence. High-voltage-activated (HVA) Ca2+channels show...
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