nregulated ACE2 mRNA in cardiac myocytes, it only reduced ACE2 activity in fibroblasts (29). In myocytes, endothelin (ET)-1 also significantly decreased ACE2 mRNA production (29). This reduction in ACE2 mRNA by Ang II or ET-1 was blocked by inhibitors of mitogen-activated protein kinase 1 (MAPK1), which suggested that Ang II and ET-1 activate extrace