Fig. 7.

Myosin light chain phosphorylation.

Coronary vascular smooth muscle contraction originates from myosin light chain (MLC) phosphorylation in the media of the artery. We measured MLC phosphorylation using Western blotting after the exposure of 1 µM serotonin in the repeated endothelial denuded site (ED). W-7, CaM inhibitors and endothelin receptor-type A antagonists (ETA) inhibited the phosphorylation of MLC. However, hydroxyfasudil, Rho-kinase inhibitors partially changed the phosphorylation level of MLC. These data indicate that repeated endothelial denudation is the cause of serotonin-induced phosphorylation of the MLC via CaM in the coronary artery. The results are shown as the means ± SEM n=8 each, #; p<0.01 vs control group, *; p<0.01 vs ED group.