depolarizationinduced

Depolarization-induced is a term used in physiology to describe cellular responses that are triggered by membrane depolarization, a shift of the resting potential toward more positive values. It denotes how a voltage change across the cell membrane leads to a cascade of electrical and chemical events in excitable cells such as neurons and muscle fibers.

In neurons, depolarization opens voltage-gated sodium channels, producing the rapid upstroke of the action potential. This is typically followed by the activation of voltage-gated potassium channels that restore the resting potential. The depolarization that accompanies the action potential also promotes calcium entry through presynaptic voltage-gated calcium channels, a key trigger for neurotransmitter release at synapses.

In muscle cells, depolarization of the sarcolemma activates excitation-contraction coupling to release calcium from internal stores. In skeletal muscle, voltage-sensing DHPRs interact with RyR1 to release Ca2+. In cardiac muscle, L-type voltage-gated calcium channels often provide the trigger that induces calcium-induced calcium release from RyR2, culminating in muscle contraction.

The descriptor also applies to other depolarization-dependent processes, including calcium-dependent exocytosis in secretory cells and various forms of stimulus-secretion coupling in endocrine tissues.

Methods to study depolarization-induced responses include patch-clamp electrophysiology to control and measure membrane potential, voltage-clamp techniques to isolate specific ionic currents, and imaging approaches such as calcium indicators or voltage-sensitive dyes. Understanding these mechanisms is fundamental to neuroscience, cardiology, and muscle physiology.