What evolutionary hypothesis could explain the heart's role in secreting a hormone that regulates renal function?

Explanation

Atrial Natriuretic Peptide or Factor (ANF) is produced due to excessive stretch of cardiac artrial cells that results in increase in blood flow to the atria of the heart. ANF increases the blood flow to the glomerulus and acts as a vasodilator on afferent glomerulus arterioles and as vasoconstrictor on efferent arterioles. It also acts antagonistically to reninangiotensin system, aldsterone and vasopressin.
Initially, 4 C-type natriuretic peptide penes CNP 1-4 were generated by chroniosomal duplications CNP3 gave rise to ANF and BPN . However, later in evolution, specific lineages of CNP genes were lost in different vertebrate classes. In mammalls, CNP-4 gene was the only CNP gene retained.