Use of protein kinase C inhibitors results in rapid [Mg(2+)](i) mobilization in primary cultured rat aortic smooth muscle cells: are certain kinase C isoforms natural homeostatic regulators of cystolic free Mg(2+).

The effects of five different protein kinase C inhibitors--calphostin C, chelerythrine, bisindolylmaleimide I, staurosporine and Gö6979--on intracellular free magnesium ([Mg(2+)](i)) content and mobilization were investigated in primary, cultured rat aortic smooth muscle cells. All these protein kinase C inhibitors significantly and rapidly increased [Mg(2+)](i) both in normal media (1.2 mM Mg(2+)) and in Mg(2+) free media. These data suggest that the increments of [Mg(2+)](i), induced by the diverse protein kinase C inhibitors, are derived from the release of bound intracellular Mg(2+) and that activation of protein kinase C isozymes are normally responsible for helping to maintain basal levels of [Mg(2+)](i) in rat aortic smooth muscle cells.