Vanadate ion inhibits actomyosin interaction in chemically skinned vascular smooth muscle

Abstract

Summary Myosin light chain phosphorylation has been shown to be an obligatory step in the activation of actomyosin interaction in vertebrate smooth muscle. Irreversible thiophosphorylation with ATP-γ-S leads to a Ca++-independent contraction in a variety of skinned smooth muscle preparations. In chemically skinned hog carotid arteries, low concentrations (less than 1 mM) of vanadate ion, a phosphate analogue, were found to abolish tension development, but did not interfere with the thiophosphorylation reaction. Vanadate ion appears then to inhibit the tension-generating binding of phosphorylated myosin to actin.