The Function Of Subunits Of Big Conductance Ca²⁺-activated K⁺ Channels In Mouse Airway Smooth Muscle

Ion channels exhibit two essential biophysical properties:selective ion conduction and the ability to open in response to appropriate stimulation.Ion channels play a crucial role in animal and plant cells.One of them is potassium channel.They are not just responsible for regulating the membrane potential,but also control the cell proliferation and hormone release.Ca²⁺-activated K⁺channels of large conductance?MaxiK or BK channels?control a large variety of physiological processes,including smooth muscle tone,neurosecretion,and hearing.BK channels are widely present in most of the cells in the body,such as smooth muscle cells,cardiac muscle cells,pituitary cells,nerve cells,and even mitochondria.Because the BK channel has many characteristics,such as activation of calcium,large conductance,multi regulation,it is very important to the life body.Thus,it has been widely studied.It has been known that the BK channel is made up of two subunits of alpha and beta.Beta subunit?beta 1⁴?in BK channel plays an important role,they are not identical.The beta 1 subunit can rapidly activate the channel,due to the voltage sensor structure,also enhance the calcium sensitivity of BK channel;Beta 2 subunit regulates channel open and close;Beta 3 subunit can quickly shut down channel;Beta subunit 4 can galvanize channel.Therefore,functions of different subunits complement each other,making the BK channel more complex and diverse.We hope to make clear to functions of different subunits of BK channels.Our results show that tracheal smooth muscle cells express BK alpha,beta 1,beta 4 subunit mRNA;BK single channel currents disappeared after inactivation of BK alpha subunit,suggesting BK alpha subunit is a core part of the BK channel pore;BK single channel currents were partially inhibited after inactivation of beta 1subunits;Following the inactivation of BK beta subunit 4,BK single channel currents were not affected.