Adrenomedullin induces expression of c-fos and AP-1 activity in rat vascular smooth muscle cells and cardiomyocytes.

The recently described hypotensive peptide adrenomedullin has been shown to activate various second messenger pathways in cells of the cardiovascular system though no genomic actions have yet been described. In cultured rat vascular smooth muscle cells, cardiomyocytes, and cardiac fibroblasts, adrenomedullin caused a rapid, but transient induction of c-fos mRNA expression in all three cell types that varied in magnitude. Adrenomedullin increased AP-1 DNA binding activities in vascular smooth muscle cells and cardiomyocytes, but not in cardiac fibroblasts. These data suggest that cardiomyocytes and vascular smooth muscle cells may be important genomic targets for this novel hormone.