Objective: 

We have shown that uncomplicated EH is associated with selective reduction in renal vasoconstriction and exaggerated natriuresis. We tested the hypotheses that the urinary excretion of specific proteins responds to saline infusion, and that EH is associated with excretion of specific proteins via exosomes (small vesicles shed by the epithelial cells lining the urinary space). Methods. EH patients without co-morbidity and matched NT subjects were studied after 4 d of standardized diet. Urine was collected before and after saline infusion (20 mmol/kg/min for 4 h). Exosomes were separated by ultracentrifugation; the membrane proteins were prepared for mass spectrometry and analyzed using C18 liquid chromatography mass spectrometry (LC MSE). Excreted proteins were quantified using ProteinLynx Global SERVER (Waters). Individual proteins were normalized to creatinine and expressed as fmol protein/mmol creatinine. Results. Some 300 proteins were identified and quantified in each urine sample. At baseline, 21 proteins were identified in two or three EH patients (n=8), but not in any NT (n=5). Six different subunits of V-type proton ATPase were identified; in NT, the subunit excretion rates all increased after saline infusion, but in EH, the response was inconsistent. Excretion of specific proteins shows larger variances in EH than in NT. Conclusion. The proteins specific for EH may reflect etiology of the disease. The large variances indicate that the EH group is heterogeneous and may be subdivided by use of this technique.