Odorants cause Ca2+ to rise in olfactory sensory neurons (OSNs) first within the ciliary compartment, then in the dendritic knob, and finally in the cell body. Ca2+ not only excites but also produces negative feedback on the transduction pathway. To relieve this Ca2+-dependent adaptation, Ca2+ must be cleared from the cilia and dendritic knob by mechanisms that are not well understood. This work focuses on the roles of plasma membrane calcium pumps (PMCAs) through the use of inhibitors and mice missing 1 of the 4 PMCA isoforms (PMCA2). We demonstrate a significant contribution of PMCAs in addition to contributions of the Na+/Ca2+ exchanger and endoplasmic reticulum (ER) calcium pump to the rate of calcium clearance after OSN stimulation. PMCAs in neurons can shape the Ca2+ signal. We discuss the contributions of the specific PMCA isoforms to the shape of the Ca2+ transient that controls signaling and adaptation in OSNs.
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