Related Experiment Video
Updated: Aug 17, 2026

Modeling Biological Membranes with Circuit Boards and Measuring Electrical Signals in Axons: Student Laboratory Exercises
Published on: January 18, 2011
The squid axon as a model for studying plasma membrane mechanisms for calcium regulation
1Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas, Caracas.
Abstract:
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.
Related Concept Videos
Action Potentials
Enlargement of the Plasma Membrane
Action Potential
Membrane potential in neurons
Neurons typically have a resting membrane potential of about -70 millivolts (mV). When they receive...
The Role of Ion Channels in Neuronal Computation
Sometimes a single EPSP is strong enough to induce an action potential in the postsynaptic neuron. However, multiple presynaptic inputs must often create EPSPs around the same time for the postsynaptic neuron to be sufficiently depolarized to fire an action potential.
Feedback Regulation of Calcium Concentration
Various transmembrane receptors, such as G protein-coupled receptors (GPCRs), elicit a response to extracellular signals by increasing cytosolic calcium. Activated GPCRs...
Action Potential
Membrane potential in neurons
Neurons typically have a resting membrane potential of about -70 millivolts (mV). When they receive...

