Calcium cooperativity of exocytosis as a measure of Ca2+ channel domain overlap

• Published in: Brain research Vol. 1398; pp. 126 - 138
• Main Authors: Matveev, Victor, Bertram, Richard, Sherman, Arthur
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 29.06.2011; Elsevier
• Subjects: Animals; Biological and medical sciences; brain; Calcium; Calcium channels; Calcium Channels - chemistry; Calcium Channels - physiology; Calcium currents; Calcium Signaling - physiology; Calcium signalling; Cell physiology; Central Nervous System - cytology; Central Nervous System - physiology; Cooperativity; Exocytosis; Exocytosis - physiology; Fundamental and applied biological sciences. Psychology; Humans; Molecular and cellular biology; Neurology; Neurotransmitter release; Protein Structure, Tertiary - physiology; Reviews; Secretion. Exocytosis; Synapses; Synapses - physiology; synaptic transmission; Synaptic vesicles; Vesicles; Current cooperativity; Calcium cooperativity; Calcium diffusion; Synaptic transmission; Calcium buffer; Exocytosis; Active zone; Modeling; Channel cooperativity; Presynaptic; Calcium; Ionic channel; Review; Diffusion
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2011.05.011

Abstract The number of Ca2+ channels contributing to the exocytosis of a single neurotransmitter vesicle in a presynaptic terminal has been a question of significant interest and debate, and is important for a full understanding of localized Ca2+ signaling in general, and synaptic physiology in particular. This is usually estimated by measuring the sensitivity of the neurotransmitter release rate to changes in the synaptic Ca2+ current, which is varied using appropriate voltage-clamp protocols or via pharmacological Ca2+ channel block under the condition of constant single-channel Ca2+ current. The slope of the resulting log–log plot of transmitter release rate versus presynaptic Ca2+ current is termed Ca2+ current cooperativity of exocytosis, and provides indirect information about the underlying presynaptic morphology. In this review, we discuss the relationship between the Ca2+ current cooperativity and the average number of Ca2+ channels participating in the exocytosis of a single vesicle, termed the Ca2+ channel cooperativity . We relate these quantities to the morphology of the presynaptic active zone. We also review experimental studies of Ca2+ current cooperativity and its modulation during development in different classes of synapses.