Stretch-activated Ion Channel - Regulation

Regulation

Stretch-activated ion channels are one of the three main types of ionotropic receptors, or channel-linked receptors. These channels open when mechanical forces of stretch or pressure is applied to the channels, causing them to undergo a conformational change. This change allows ions to pass through. The channels may also be pulled open due to tension on the membrane itself. Opening the channels allows ions to which they are permeable to flow down their electrochemical gradients into or out of the cell, causing a change in membrane potential.

All types of stretch-activated ion channels respond to mechanical stimuli with a similar mechanism. A stimulus resulting from a deformation of the capsule on the afferent neuron causes a stretch in the membrane. This mechanical deformation causes stretch-sensitive channels to have an increased probability of opening. A depolarization of the afferent nerve fiber occurs as the stretch-activated cation channel opens. An action potential fires if the cell is depolarized above threshold and it propagates to the CNS. The sensory stimuli that excite stretch-activated channels are regulated by Ab and Aa nerve fibers. These fibers have low thresholds and originate from mechanosensory neurons in the dorsal root ganglion. ). Channels that have traditionally been known as just “voltage-“ or “ligand-gated” have also been found to be mechanically sensitive as well. Channels exhibit mechanical sensitivity as a general property. However, mechanical stress affects various types of channels in different ways. Voltage and ligand gated channels can be modified slightly by mechanical stimulation, which might change their responsiveness or permeability slightly, but they still respond primarily to voltage or ligands, respectively.