[Estimation of the intrarenal hemodynamics in patients with primary aldosteronism]

Intrarenal hemodynamics were estimated in patients with primary aldosteronism (PA) using the Gomez's equations and by analyzing their renal function curve. The study was performed in 6 patients with PA for 2 weeks; they were given a regular sodium diet (12-15 g/day) in the 1st week and a sodium restricted diet (1-3 g/day) in the 2nd week. Blood pressure and urinary sodium excretion (UNaV) were measured on the last three days of each stage. Glomerular filtration rate (GFR) and renal plasma flow rate (RPF) were also measured on the regular sodium diet. Afferent (RA) and efferent (RE) arteriole resistances, and glomerular hydrostatic pressure (PG) were calculated using Gomez's equations. UNaV was plotted on the ordinate as a function of mean blood pressure (MAP) on the x-axis. Assuming that the difference between MAP and the x-intercept of this renal function curve represents the effective filtration pressure, RA, PG and gross filtration coefficient of capillaries (KFG) were also calculated. GFR and RPF were 102 +/- 6, 469 +/- 27 ml/min, respectively. Estimated RA (6600 +/- 700 dyns.sec.cm-5) was markedly elevated, while RE (2500 +/- 100 dyns.sec.cm-5), PG (57 +/- 2 mmHg) and KFG (0.195 +/- 0.041 [ml/sec]/mmHg) remained normal. The intrarenal hemodynamic parameters obtained by analyzing the renal function curve were consistent with those by Gomez's equations. Recently, in DOCA-salt hypertension, an animal model analogous to human PA, PG has been reported to be increased, leading to renal damage. However, the increase in RA was as marked as seen in essential hypertension, and further the increase in PG was not observed in the patients of this study. Thus, it is not clear whether there is a meaningful relationship between glomerular hypertension and renal damage in PA as reported in DOCA-salt hypertension.