What is the current-clamp method?
The current-clamp method detects transmembrane voltage change resulting from ion channel activity. This technique allows the investigator to control the amount of current injected into the cell, thereby controlling the transmembrane potential.
Figure 1. (Left) Cell membrane behavior is compared with an electrical current. The lipid bilayer acts as a capacitor while the ion channel acts as a conductance. (Right) A membrane behaves electrically like a capacitance in parallel with a resistance.
In a current-clamp experiment, one applies a known current and measures the change in membrane potential (Vm) caused by the applied current. This type of experiment mimics the current produced by a synaptic input.
Figure 2. If we apply a pulse of current (I) to the circuit, the current first charges up the capacitance, causing a slight time delay (t), then changes the voltage (V).
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