UROMODULIN--A LINK BETWEEN SODIUM EXCRETION AND ALTERATION IN CIRCADIAN BLOOD PRESSURE PATTERN IN PREHYPERTENSIVES/UROMODULIN - POVEZNICA IZMEDU NATRIURIJE I DNEVNOG RITMA ARTERIJSKOG TLAKA KOD PREDHIPERTONICARA

Although changes in dietary sodium intake alter blood pressure (BP) in salt-sensitive individuals, pathophysiological mechanisms are still unknown. It has been reported that uromodulin is involved in sodium tubular transport, and genome-wide association studies pointed to UMOD gene as one of the most important gene candidates for arterial hypertension. Our aim was to analyze urinary uromodulin, salt intake and BP in 326 young middle-aged subjects (mean age 36[+ or -]8 years, 49.4% male). In a subgroup of 175 individuals, ambulatory blood pressure monitoring and echocardiogram were performed. Uromodulin was determined by ELISA. According to the JNC-7 criteria, subjects were classified as optimal BP (n=103, men 72%), prehypertension (PHT) (n=143, men 43%) and hypertension (HT) (n= 80, men 38%). There were no differences in age, salt intake, estimated glomerular filtration rate, sodium excretion and uromodulin among BP groups. However, in PHT subjects, uromodulin was positively associated with fractional sodium excretion and negatively with 24-h sodium excretion and diastolic BP dip. These findings point to the effect of uromodulin on sodium reabsorption along the nephron and consequently circadian BP alteration in prehypertensives. Promjene u dnevnom unosu kuhinjske soli u osoba osjetljivih na sol utjecu na arterijski tlak (AT), ali tocan patofizioloski mehanizam jos nije u potpunosti razjasnjen. Cilj ove studije je bio istraziti izlucivanje uromodulina (UM) i natrija mokracom i povezanost s AT u mladih odraslih osoba. U 326 ispitanika (medijan dobi 36, IQR 18-48, 64,6% muskarci) analizirani su uzorci krvi i mokrace uzeti nataste i izmjeren je AT u ordinaciji, a kod 175 ispitanika ucinjeno je kontinuirano mjerenje arterijskoga tlaka. UM je odreden metodom ELISA. Prema klasifikaciji JNC-7 optimalni AT, predhipertenzija (PHT) i hipertenzija (HT) su dijagnosticirani u 103 (72% m), 143 (43% m) i 80 (38% m) ispitanika. Nije bilo razlike u dobi, unosu kuhinjske soli, procijenjenoj stopi glomerularne filtracije niti u izlucivanju natrija i UM mokracom izmedu kategorija AT. Uocena je pozitivna povezanost UM s frakcijskom ekskrecijom natrija, a negativna s 24-satnom natriurijom i nocnim snizenjem dijastolickoga AT u PHT. Ovi rezultati upucuju na povezanost UM s tubularnom reapsorpcijom natrija i promjenama dnevnoga ritma AT u predhipertonicara. Kljucne rijeci: Uromodulin; Natriurija; Kontinuirano mjerenje arterijskog tlaka; Predhipertenzija Key words: Uromodulin; Sod