Processing of artery smooth muscle cells patch and the properties of largeconductance calcium-activated potassium channels

Objective: To investigate the processing of the artery smooth muscle cells patch and to observe the properties of large-conductance calcium-activated potassium channels in them.Methods: The humans mesenteric artery was dissociated from human mesenteriolum,and single smooth muscle cells were isolated by enzyme and put into symmetric high potassium solution.The channel current was recorded by using patch clamp and the data were analyzed by the computer.The processing of three kinds of ptches of artery smooth muscle cell and the characteristics of BK_Ca were observed.Results: In the experiment,cell attached,inside-out and whole cell recording patches were produced respectively on the cytomembrane of mesenteric artery smooth muscle.BK_Ca channels of smooth muscle cells isolated by enzyme were sensitive to[Ca²⁺]i and dependant on voltage;the channels opened more frequently with the increase of free[Ca²⁺]i and membrane potential.The conductance of enzymatic smooth muscle cells in this experiments was 198.6±38.09 pS;The channels were sensitive to TEA⁺:when 50 mmol/L TEA⁺ was used,these channels were entirely blocked.Conclusions: The experiments suggested that BK_Ca channels in smooth muscle cells isolated by enzyme were sensitive to Ca²⁺,dependent of voltage sensitive to TEA⁺ and had the properties of large conductance.