Calcium and the Action Potential in Smooth Muscle
In most excitable membranes the action potential is produced by an inward movement of Na ions across the membrane. The maximum rate of rise in nerve is about 500 V/sec and is roughly proportional to the external Na concentration (Hodgkin & Katz, 1949). The action potential is abolished in Na-free solution. It is also known, however, that in some crustacean muscle fibres, Ca ions, not Na ions, carry the inward current for the production of the action potential (Hagiwara & Naka, 1964). The removal of Na ions from the external solution does not, therefore, change the size or the shape of the action potential.
KeywordsSpike Activity External Solution Membrane Resistance Locke Solution Constant Current Pulse
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