Ion channels in mesangial cells: function, malfunction, or fiction.

Ion channels in glomerular mesangial cells from humans, rats, and mice have been studied by electrophysiological, molecular, and gene-knockout methods. Two channels, a large, Ca(2+)-activated K(+) channel (BK) and a store-operated Ca(2+) channel (SOCC), can be defined with respect to molecular structure and function. Human BK, comprised of a pore-forming alpha-subunit and an accessory beta1-subunit, operate as Ca(2+)-sensing feedback modulators of contractile tone. SOCC have also been characterized in a mouse cell line; they are comprised of molecules belonging to the transient receptor potential subfamily.