The squid axon as a model for studying plasma membrane mechanisms for calcium regulation

Calcium movement across plasma membranes occurs mainly by three routes: voltage-dependent calcium channels, adenosine 5'-triphosphate-driven calcium pump, and Na+-Ca2 exchange. The regulation of the intracellular ionized calcium is the consequence of two parallel calcium transport mechanisms: a...

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Bibliographic Details
Published in:Hypertension (Dallas, Tex. 1979) Tex. 1979), 1987-11, Vol.10 (5 Pt 2), p.I15-I19
Main Authors: DiPolo, R, Beaugé, L
Format: Article
Language:English
Subjects:
Animals
Axons - metabolism
Biological Transport
Calcium - metabolism
Calcium-Transporting ATPases - metabolism
Carrier Proteins - metabolism
Cell Membrane - metabolism
Decapodiformes
Ion Channels - drug effects
Ion Channels - metabolism
Models, Biological
Muscle Contraction
Muscle Tonus
Muscle, Smooth, Vascular - physiology
Sodium - metabolism
Sodium-Calcium Exchanger
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Summary:Calcium movement across plasma membranes occurs mainly by three routes: voltage-dependent calcium channels, adenosine 5'-triphosphate-driven calcium pump, and Na+-Ca2 exchange. The regulation of the intracellular ionized calcium is the consequence of two parallel calcium transport mechanisms: a high affinity, low capacity system responsible for extruding calcium during resting conditions (calcium pump) and a low affinity and high capacity system (Na+-Ca2 antiporter). This last system is designed to extrude calcium ions when intracellular calcium rises above certain levels and also to lead calcium ions into the cell under conditions that favor the reverse mode of operation of the exchanger. This short review provides an analysis of the most conspicuous features of the two membrane transport mechanisms determined in dialyzed squid axons with special emphasis on both the complexity of the Na+-Ca2+ exchange system and its marked asymmetry.
ISSN:0194-911X
1524-4563
DOI:10.1161/01.HYP.10.5_Pt_2.I15