title: Plasmin in urine from patients with type 2 diabetes and treatment-resistant hypertension activates ENaC in vitro.
abstract: BACKGROUND
  Aberrant filtration of plasminogen from plasma and subsequent activation to plasmin in the urinary space may activate proteolytically the epithelial sodium channel, ENaC. In conditions with chronic albuminuria, this may cause hypertension. It was hypothesized that patients with type 2 diabetes mellitus (T2DM) and treatment-resistant hypertension excrete plasmin(ogen) in urine in proportion to albumin and that plasmin confers to urine the ability to activate ENaC.
  
  
  METHODS
  Patients (n = 113) with T2DM and resistant hypertension, defined as systolic blood pressure (SBP) more than 130 mmHg and/or diastolic blood pressure (DBP) more than 80 mmHg despite use of at least three drugs with one diuretic and one renin-angiotensin system inhibitor, were included. Urine was analyzed for albumin, creatinine, plasmin(ogen), protease activity, and ability to activate inward current in single collecting duct cells.
  
  
  RESULTS
  Mean ambulatory SBP/DBP was 143 ± 1/77 ± 0.7 mmHg; HbA1c 7.35%; and eGFR 81.0 ml/min per 1.73 m (geometric means). Patients with microalbuminuria (39%) and macroalbuminuria (13%) displayed significantly elevated levels of urinary plasmin(ogen) normalized to urine creatinine compared with patients with normal excretion of albumin (48%). Urinary plasminogen correlated significantly to urine albumin. Western immunoblotting and gelatine zymography confirmed active plasmin in urine samples from patients with microalbuminuria and macroalbuminuria. Single collecting duct cells displayed significantly increased, amiloride-sensitive, inward current when superfused with urine from albuminuric patients compared with patients with normal albumin excretion. Urinary plasminogen/creatinine ratio correlated significantly with 24-h ambulatory blood pressure.
  
  
  CONCLUSIONS
  Aberrant presence of plasmin in preurine may inappropriately activate ENaC in patients with type 2 diabetes and microalbuminuria. This may contribute to treatment-resistant hypertension.
authors.affiliation: aDepartment of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark bDepartment of Endocrinology, Research Unit for Cardiovascular and Metabolic Prevention cDepartment of Nephrology, Odense University Hospital, Odense, Denmark.
authors.forename: Kristian B
authors.initials: KB
authors.lastname: Buhl
authors.forename: Christina S
authors.initials: CS
authors.lastname: Oxlund
authors.forename: Ulla G
authors.initials: UG
authors.lastname: Friis
authors.forename: Per
authors.initials: P
authors.lastname: Svenningsen
authors.forename: Claus
authors.initials: C
authors.lastname: Bistrup
authors.forename: Ib A
authors.initials: IA
authors.lastname: Jacobsen
authors.forename: Boye L
authors.initials: BL
authors.lastname: Jensen
mesh_terms: D000419:Albuminuria / Q000503:physiopathology; D001794:Blood Pressure; D003404:Creatinine / Q000652:urine; D003924:Diabetes Mellitus, Type 2 / Q000652:urine*; D004351:Drug Resistance; D053503:Epithelial Sodium Channels / Q000502:physiology*; D005341:Fibrinolysin / Q000652:urine*; D006801:Humans; D006973:Hypertension / Q000188:drug therapy / Q000209:etiology / Q000652:urine*; D010958:Plasminogen / Q000652:urine
chemical_list: D053503:Epithelial Sodium Channels; D010958:Plasminogen; D003404:Creatinine; D005341:Fibrinolysin