Urinary Prostasin: A Possible Biomarker for Renal Pressure Natriuresis in Black Adolescents

Prostasin is a membrane-bound/secretive serine protease interacting with aldosterone and the epithelial sodium channel in the kidney. We and others have previously proposed the concept of stress-induced pressure natriuresis (SIPN) where increased urinary sodium excretion (UNaV) is coupled with elevated blood pressure (BP) in response to behavioral stress in normotensive adolescents. This study thus aimed to test the relationship between prostasin and pressure natriuresis using the SIPN model. A cohort of 102 normotensive black adolescents (mean age: 17.0 +/- 1.2 y; 56% females) were placed on a controlled sodium (4000 200 mg/d) and potassium (2600 200 mg/d) diet for three days before testing. The SIPN protocol consisted of a 1-h baseline period, a 1-h stress period (competitive video game), and a 1-h recovery period. During the stress period. BP elevation was coupled with an increase in UN V. Urinary prostasin concentration had more than a 2-fold reduction from baseline (38.4 +/- 32.7 ng/mL) to stress (17.2 +/- 16.0 ng/mL), and further declined during recovery (12.1 +/- 16.2 ng/mL) (p < 0.001). Urinary prostasin was inversely correlated with UN,,V during stress (r = -0.43, p = 0.0001), even after being normalized by urinary creatinine. Our data suggest that urinary prostasin could be a novel biomarker and/or mechanism for renal pressure natriuresis in normotensive black adolescents. (Pediatr Res 65: 443-446, 2009)