The function of isolated perfused kidneys in post-DOCA phase of DOCA-salt hypertension was evaluated in rats subjected to DOCA-salt treatment either from youth or only in adulthood. Post-DOCA-salt hypertension was more severe in young than in adult animals. Kidneys isolated from young post-DOCA-salt hypertensive rats had higher renal vascular resistance when compared to adult ones. Perfusion of isolated kidneys over a wide range of perfusion pressure (110-170 mm Hg) has shown similar decrease of glomerular filtration, filtration fraction, diuresis and natriuresis in both age groups of DOCA-salt treated groups. Perfusion pressure-sodium excretion curves had reduced slope and were shifted to the right in both hypertensive groups, indicating huge glomerular damage. Nevertheless, the relative difference in glomerular filtration and sodium excretion between hypertensive rats and age-matched normotensive controls was always greater in younger animals. These results suggest that the more pronounced changes in glomerular hemodynamics and filtration could be involved in higher blood pressure-response of young animals to DOCA-salt treatment.