The correct answer is "atrial natriuretic peptide" or "ANP". ANP is secreted by the the atria and the muscle cells of the heart. ANP primarily functions to increase sodium excretion (hence the term natriuretic) which facilitates osmotic diuresis, since there will be a high amount of solute in the renal tubules, this will exert an osmotic force that draws water and facilitate diuresis. This will eventually result to increased urinary output and dehydration.
