(1)
Department of Anaesthesia, Royal Free Hospital, London, UK
K channels are present in all the cells and maintain resting membrane potentials. Closing of K channel leads to depolarisation.
Voltage-gated K channels: get activated by the change in cell membrane potential. Twelve different subtypes are seen (Kiv1–Kiv12). Nerve injury decreases K currents causing hyperalgesia. 4-Aminopyridine and tetraethylammonium can block voltage-gated K channels. Prostaglandins mediate their analgesic effects through voltage-gated K channels.
Calcium-activated K channels: they are divided into three families:
Large conductance
Intermediate conductance
Small conductance
All of these are activated when cytoplasmic concentration of calcium is increased.
Inwardly rectifying K channels: they alter the direction of ionic flow. They facilitate influx more than the efflux. They are further divided into seven families (Kiv1–Kiv7). Gir 3(G-protein-regulated inwardly rectifying K channel) is involved with nociception.Full access? Get Clinical Tree