Natriuretic Hormone

Abstract

Until about 1957 it was generally accepted that the regulation of renal sodium excretion was dependent solely upon changes in

(a) glomerular filtration rate (Factor 1) and

(b) the activity of the renin-angiotensin-aldosterone system (Factor 2).

coupled with the effect of changes in intrarenal haemodynamics and physical factors, such as hydrostatic pressure surrounding renal tubules, and plasma protein osmotic pressure in peritubular capillaries.

Since that time, however, evidence has gradually been accumulated to suggest that these are not the only factors which are relevant in this context, and the existence of a humoral inhibitor of renal sodium reabsorption has therefore been postulated. This ‘third factor' has been given the name of natriuretic hormone, and indications of its presence have been found in two principal situations. These are

(a) 'Sodium escape’ during chronic mineralocorticoid administration

(b) Volume expansion with

                                 (i) isotonic saline

                                 (ii) blood