Physiology of natriuretic peptides: The volume overload hypothesis revisited

Table 1 Established facts

Already known fact 1	Volume overload (stretch or pressure) stimulates the synthesis and release of natriuretic peptides
Already known fact 2	Natriuretic peptides cause natriuresis, diuresis, vasodilatation and plasma shift

Table 2 Novel insights

New information 1	Natriuretic peptide system responds to oxygen tension (hypoxia-response elements in the promoter sequence of ANP and BNP genes). Volume overload causes wall stress and changes the consumption or diffusion of oxygen in heart
New information 2	The result of natriuresis, diuresis and plasma shift is volume contraction and increased oxygen-carrying capacity per unit volume of blood. Oxygen transport will be enhanced

ANP: Atrial natriuretic peptide; BNP: Brain natriuretic peptide.