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Calcium oscillates in and out!

Ca²⁺ waves, Ca²⁺ oscillations, local Ca²⁺ spikes and puffs – intracellular Ca²⁺ signalling is very complex. Well, it gets worse: Annunziata De Luisi and Aldebaran Hofer now reveal that extracellular Ca²⁺ levels oscillate too (see p. 1527). They show that stimulation of the extracellular Ca²⁺ receptor CaR (a G-protein-coupled receptor that monitors extracellular Ca²⁺) produces oscillations in intracellular Ca²⁺ levels in clusters of adjacent HEK293 cells. Since the oscillations are unaffected by gap junction inhibitors, the authors speculated that they might be transmitted by release of Ca²⁺ through plasma membrane Ca²⁺ pumps (PMCAs) and its activation of CaRs on neighbouring cells. Indeed, De Luisi and Hofer demonstrate that PMCA inhibitors (e.g. HgCl₂) block the response, as do buffers that maintain extracellular Ca²⁺ at a constant level (e.g. BAPTA free acid). They also use the near-membrane Ca²⁺ probe fura-C₁₈ to show that activation of CaRs produces local oscillations in the extracellular Ca²⁺ concentration. Since the CaRs and PMCAs appear to reside in specific membrane microdomains, the authors suggest that local extracellular Ca²⁺ oscillations in these regions help to reinforce the intracellular oscillations.

Related articles in JCS:

Evidence that Ca²⁺ cycling by the plasma membrane Ca²⁺-ATPase increases the `excitability' of the extracellular Ca²⁺-sensing receptor

Annunziata De Luisi and Aldebaran M. Hofer
JCS 2003 116: 1527-1538. [Abstract] [Full Text]  

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Related articles in JCS Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Search for Related Content