Abstract The vasoactive neuropeptide endothelin stimulated phosphorylation of specific proteins in rat brain microvessels. Major effects were observed with endothelin-1. These effects were dose- and time-dependent. Among substrates for kinase actions, the 17.5 KDa and 80 KDa proteins were mainly affected by endothelin-1. It was demonstrated that the 80 KDa protein affected corresponds to MARCKS (myristoylated alanine-rich C kinase substrate), a specific substrate for protein kinase C action.