Inhibition of myosin light chain phosphorylation in cultured smooth muscle cells by HA1077, a new type of vasodilator.

When cultured smooth muscle cells were stimulated sequentially by concanavalin A and fetal calf serum, the cells rounded up, and there was an accompanying mono- and diphosphorylation of the 20 kDa myosin light chain. HA1077, a new type of vasodilator, inhibited both the cell rounding and the light chain phosphorylation in a concentration dependent manner. Since HA1077 inhibits myosin light chain kinase, in vitro, we propose that this vasodilator presumably inhibits cell rounding by limiting myosin light chain phosphorylation.