Stress-induced renal alterations in normotensives offspring of hypertensives and in hypertensives

Background Scarce information is available on stress-induced renal behavior in humans, especially in normotensives offspring of hypertensives (HP) and in hypertensives (HT). Methods Ten HP and 10 HT were compared to 10 normotensives with normotensive parents (NP). Systolic blood pressure (SBP) and renal functional parameters were determined during rest and stress periods. Results The stress SBP reactivity was significantly (P< .05) higher in HP than in NP and HT. At rest, HP were characterized by a significantly (P< .05) higher glomerular filtration rate. Stress significantly reduced glomerular filtration rate (−14 ± 4 mL/min/1.73 m2, P< .05) only in HT. Renal plasma flow significantly (P< .05) decreased during stress in NP (−35 ± 16 mL/min/1.73 m2) and in HT (−49 ± 25 mL/min/1.73 m2), whereas it did not change in HP. The resulting filtration fraction increased significantly during stress only in NP (1.5% ± 0.6%, P< .05). Despite the increase in BP, stress induced a similar decrease in sodium excretion rate in NP (−52 ± 26 μmol/min) and in HT (−56 ± 24 μmol/min). The stress-induced sodium reabsorption occurred only in the proximal part of the tubules (lithium clearance). In HP, stress did not alter either sodium excretion rate or plasma renin activity. Conclusions: The stress-induced renal modifications are characterized by an efferent vasoconstriction and a paradoxical increase in sodium reabsorption that occurred in the proximal part of the tubules in NP. In HP, genetically at risk of hypertension, basal renal alterations may explain a different stress-induced renal behavior. In HT, stress-induced increase in sodium reabsorption may be involved in the sustained BP level.