Stretch-induced triphosphorylation of myosin light chain and myogenic tone in canine basilar artery.

The relationship between phosphorylation of 20,000 Da myosin light chain (MLC20) and contraction in response to mechanical stretch was investigated in the canine basilar artery. A slow stretch (at a rate of 1 mm/s and a stimulus period for 15 min) increased triphosphorylated MLC20 despite lowered intracellular calcium concentration and mechanical activities, such as myogenic tone, shortening velocity and stiffness of the artery. Nicardipine, a Ca2+ channel blocker, and ML-9, a myosin light chain kinase (MLCK) inhibitor, partially inhibited the stretch-induced MLC20 phosphorylation.