An increase in sodium conductance is associated with which of the following?
ExplanationThe end-plate potential in skeletal muscle is produced by an influx of sodium into the cell, which results from the increase in sodium permeability that occurs with acetylcholine binding to the nicotinic receptors on the membrane of the motor end plate. Acetylcholine binding at the motor end plate also increases the potassium conductance of the membrane. The plateau phase of ventricular muscle action potentials and the upstroke of smooth muscle action potentials are produced by an increase in calcium conductance. An increase in potassium conductance is responsible for the downstroke of the action potential. The refractory period is caused by an increase in potassium conductance and a decrease in the number of sodium channels available to produce an action potential (i.e., sodium channel inactivation).
