A negative regulation of smooth muscle contraction resulting in relaxation of vascular smooth muscle. The relaxation is mediated by a decrease in the phosphorylation state of myosin light chain. This can be achieved by removal of calcium from the cytoplasm to the sarcoplasmic reticulum lumen through the action of Ca2+ ATPases leading to a decrease myosin light chain kinase activity, and through calcium-independent pathways leading to a increase in myosin light chain phosphatase activity. [ GOC:TermGenie GOC:dph http://purl.obolibrary.org/obo/go/references/0000058 GOC:BHF_miRNA GOC:rph http://www.ncbi.nlm.nih.gov/pubmed/27389411 GOC:BHF http://www.ncbi.nlm.nih.gov/pubmed/15867178 http://www.ncbi.nlm.nih.gov/pubmed/19996365 ]