Limits of Calcium Clearance by Plasma Membrane Calcium ATPase in Olfactory Cilia

作者：Kleene Steven J^*

来源：PLos One, 2009, 4(4): e5266.

DOI：10.1371/journal.pone.0005266

Background: In any fine sensory organelle, a small influx of Ca(2 ) can quickly elevate cytoplasmic Ca(2 ). Mechanisms must exist to clear the ciliary Ca(2 ) before it reaches toxic levels. One such organelle has been well studied: the vertebrate olfactory cilium. Recent studies have suggested that clearance from the olfactory cilium is mediated in part by plasma membrane Ca(2 )-ATPase (PMCA).
Principal Findings: In the present study, electrophysiological assays were devised to monitor cytoplasmic free Ca(2 ) in single frog olfactory cilia. Ca(2 ) was allowed to enter isolated cilia, either through the detached end or through membrane channels. Intraciliary Ca(2 ) was monitored via the activity of ciliary Ca(2 )-gated Cl(-) channels, which are sensitive to free Ca(2 ) from about 2 to 10 mu M. No significant effect of MgATP on intraciliary free Ca(2 ) could be found. Carboxyeosin, which has been used to inhibit PMCA, was found to substantially increase a ciliary transduction current activated by cyclic AMP. This increase was ATP-independent.
Conclusions: Alternative explanations are suggested for two previous experiments taken to support a role for PMCA in ciliary Ca(2 ) clearance. It is concluded that PMCA in the cilium plays a very limited role in clearing the micromolar levels of intraciliary Ca(2 ) produced during the odor response.

• 出版日期2009-4-23