Low-voltage-activated (LVA) T-type Ca2 + channels differ from their high-voltage-activated (HVA) homologues by unique biophysical properties. Hence, whereas HVA channels convert action potentials into intracellular Ca 2 + elevations, T-type channels control Ca2 + entry during small depolarizations around the resting membrane potential. They play an important role in electrical activities by generating low-threshold burst discharges that occur during various physiological and pathological forms of neuronal rhythmogenesis. In addition, they mediate a previously unrecognized function in the control of synaptic transmission where they directly trigger the release of neurotransmitters at rest. In this review, we summarize our present knowledge of the role of T-type Ca2 + channels in vesicular exocytosis, and emphasize the critical importance of localizing the exocytosis machinery close to the Ca2 + source for reliable synaptic transmission. This article is part of a Special Issue entitled: Calcium channels.
展开▼
