loss of polarization; especially : loss of the difference in charge between the inside and outside of the plasma membrane of a muscle or nerve cell due to a change in permeability and migration of sodium ions to the interior
The main ion responsible for depolarizing the sarcolemma is sodium (Na+).
A depolarizing graded potential is a change in membrane potential that makes the inside of the cell less negative. This can occur due to the influx of positively charged ions such as sodium into the cell. Depolarizing graded potentials are involved in generating action potentials in excitable cells.
The term depolarizing agent has been used to denote a substance used in a primary cell to prevent buildup of hydrogen gas bubbles.A battery depolarizing agent takes up electrons during discharge of the cell; therefore, it is always an oxidizing agent.
It is a non-depolarizing muscle relaxant, apparently.
Depolarizing neuromuscular blocking drugs, like succinylcholine, cause initial depolarization of the muscle cell membrane followed by prolonged depolarization. Non-depolarizing drugs, like rocuronium, block the action of acetylcholine at the neuromuscular junction without causing depolarization.
QRS wave
I believe you're thinking of succinylcholine.
The period when the atria are depolarizing is known as the P wave on an electrocardiogram (ECG). This represents the electrical activity as the impulse spreads through the atria, causing them to contract and pump blood into the ventricles.
Sodium ions are mainly responsible for depolarizing the sarcolemma when acetylcholine receptors open. Sodium influx leads to depolarization of the cell membrane, initiating an action potential.
The P wave is the first wave in an ECG complex, and it results from the atria depolarizing. It may not be present in arrhythmias where the atria do not necessarily depolarize, such as junctional or ventricular escape rhythms, and at times when the atria are depolarizing abnormally this will be reflected in the P wave's replacement by abnormal waves, such as the low-amplitude "squiggle" seen in atrial fibrillation, or the "sawtooth" pattern seen in atrial flutter.
The Na+ diffusing into the axon during the first phase of the action potential creates a depolarizing current that brings the next segment, or node, of the axon to threshold.
Turbocuarine is a synthetic compound that antagonizes muscle relaxant effects caused by non-depolarizing neuromuscular blocking agents. It can be used to reverse the effects of neuromuscular blockade in certain medical procedures.