PHYSIOLOGICAL-ROLE AND DIURETIC EFFICACY OF ATRIAL-NATRIURETIC-PEPTIDE IN HEALTH AND CHRONIC RENAL-DISEASE

In recent years, different clinical studies have provided new informat ion on the pathophysiological role and diuretic effectiveness of atria l natriuretic peptide (ANP) in subjects with normal renal function and patients with chronic renal disease. Plasma ANP (pANP) was increased by infusion (it the lowest doses ever tested in humans who were on low salt diet to tho levels that the same subjects gained when on a norma l salt dirt; ANP accounted for at least 40% of the increase of natriur esis. Similarly, ANP appeared to be mainly involved in the physiologic al down-regulation of salt excretion (that is, during the shift from a normal to low-sodium diet). Interestingly, data have been also attain ed on the efficacy of ANP as diuretic agent when administered at a low nonhypotensive dosage in normals as well as CRF patients. Indeed, low -dose, ANP promoted a marked increase of sodium excretion in CRF patie nts tu the same levels observed in normals, likely because the renal p atients exhibited a more marked pANP increment secondary to the lower renal catabolism of the infused hormone, Moreover, aldosterone suppres sion was greater in CRF patients with respect to normals. Furthermore, the fractional urinary excretion of cGMP increased more in CRF patien ts than in normals. Finally, ANP infusion augmented the urinary losses of the main solutes retained in CRF (urea, potassium, phosphorous) wi th a significant decrease in the plasma levels. Hence, ANP per se not only plays a significant role in the up- and down-regulation of sodium excretion in healthy stale and chronic renal disease. bu; it may also be considered to be a powerful and unique diuretic agent in CRF at no nhypotensive dosages.