What is use dependent blockade?
Modulation of the reduction of fast inward sodium current by local anesthetics due to changes in electrical activity has been termed use-dependent block (Courtney 1975).
What is state dependent blockade?
When a drug exhibits greater affinity for 1 or 2 states of the channel than it does for the third, it is considered state dependent. When a drug exhibits greater affinity for the open or inactivated states than it does for the resting state, it is considered use dependent.
How does blocking sodium channels cause numbness?
The local anaesthetic works by moving to the inside of the cell then binding to the ‘sodium channel’ and so blocking the influx of sodium ions. This block stops nerve conductance and prevents further signals reaching the brain (C).
Is lidocaine use-dependent?
Lidocaine inhibition of voltage-gated sodium currents involves complex voltage and use dependence that is thought to be crucial for many of the therapeutic effects.
What happens when you block if channels?
Therefore, blocking these channels slows (delays) repolarization, which leads to an increase in action potential duration and an increase in the effective refractory period (ERP). Reentry occurs when an action potential reemerges into normal tissue when that tissue is no longer refractory.
What happens if voltage-gated sodium channels are blocked?
Blocking voltage-gated sodium channels (NaV) will prevent action potential initiation and conduction and therefore prevent sensory communication between the airways and brainstem. In so doing, they would be expected to inhibit evoked cough independently of the nature of the stimulus and underlying pathology.
What happens if voltage-gated calcium channels are blocked?
Failure of these calcium channels can result in migranes, ataxia, and also other neurological diseases. Calmodulin is a specific calcium channel sensor, and regulates the functions of the channel.
How do drugs block sodium channels?
A class of drugs that act by inhibition of sodium influx through cell membranes. Blockade of sodium channels slows the rate and amplitude of initial rapid depolarization, reduces cell excitability, and reduces conduction velocity.
What is an example of a sodium channel blocker?
Class IB Sodium Channel Blockers Example class IB medications include: lidocaine, tocainide, phenytoin, and mexiletine.