CA2+-IONOPHORE A23187 AND THE CA2+-MOBILIZING HORMONES SEROTONIN, VASOPRESSIN, AND BRADYKININ INCREASE MITOCHONDRIALLY BOUND HEXOKINASE IN MUSCLE

We show that a rise in cytosolic-free Ca2+ in muscle, induced by Ca2+-ionophore A23187 or by the Ca2+-mobilizing hormones serotonin, vasopressin, and bradykinin, increases the binding of hexokinase to mitochondria in muscle. This increase could be prevented by treatment with the calmodulin antagonists trifluoperazine or CGS 9343B (a novel, potent, and selective inhibitor of calmodulin activity) which strongly suggests that calmodulin is involved in the Ca2+-induced binding of the enzyme to muscle mitochondria. © 1992.