MUSCLE PHYSIOLOGY

Detailed explanation-1: -In skeletal muscle cells, voltage-gated Ca2+ channels in the transverse tubule membranes interact directly with ryanodine-sensitive Ca2+ release channels in the sarcoplasmic reticulum and activate them to initiate rapid contraction (Catterall 1991; Tanabe et al. 1993).

Detailed explanation-2: -Voltage-gated calcium channels (VGCCs), also known as voltage-dependent calcium channels (VDCCs), are a group of voltage-gated ion channels found in the membrane of excitable cells (e.g., muscle, glial cells, neurons, etc.) with a permeability to the calcium ion Ca2+.

Detailed explanation-3: -At resting state, voltage-gated calcium channels are in a closed conformation. When the membrane is depolarized, they are open. These channels initiate the release of neurotransmitters at synapses, and have a powerful influence on synaptic strength.

Detailed explanation-4: -These channels activate at approximately −40 mV, have fast activation (Borst and Sakmann, 1998) and have relatively slow inactivation rates relative to the duration of an action potential (Forsythe et al., 1998), such that minimal inactivation occurs even during repetitive stimulation (Wang and Kaczmarek, 1998).

Detailed explanation-5: -In the nervous system, they are involved in signal transduction and are implicated in synaptic plasticity. Store-operated calcium channels are located on the membrane of the endoplasmic/sarcoplasmic reticulum. They play an essential role in maintaining a constant store of calcium when required by the cell.