EDN1 and cardiac hypertrophy: Given evidence already outlined that DAG signals enhance Ca2+ and Na+ influx in cardiac myocytes; the simple hypothesis clearly emerges that hormonal activators of hypertrophy programs, such as endothelin-1 (ET-1), angiotensin-2 (AT-2), and catecholamines, promote joint Ca2+ and DAG signaling that becomes linked in a positive feedback loop that supports the initiation of cardiac hypertrophy programs.