What do the hormones aldosterone and atrial natriuretic peptide do?

Aldo and ANP: Hi. Aldosterone (aldo) tends to promote sodium reabsorption (retention) and potassium excretion by the kidney tubule. ANP, as the name implies, tends to promote urinary sodium excretion, and is somewhat regulated by how much sodium (i.e., salt) is in the diet. We use an aldo analog, fludrocortisone, clinically for people who can't make aldo.

Aldo and Nat peptide: Aldo comes from the adrenal and acts on the mineralocorticoid receptor in the kidney and elsewhere. It makes the kidney retain salt. So it keeps you from dying of salt depletion. ANP comes from the heart and increases the excretion of salt and water in part by blocking aldo. It keeps you from dying when you drink very salty water or your body salt gets too high.