IgA nephropathy with early kidney disease is associated with increased arterial stiffness and renin-angiotensin system activity.
BACKGROUND
IgA nephropathy is associated with increased cardiovascular risk, though whether this is due to loss of kidney function or proteinuria is unclear.


METHODS
For this study 10 normotensive IgA nephropathy subjects with early kidney disease (41±5 yrs, glomerular filtration rate (GFR) 87±9 ml/min, proteinuria 720±300 mg/d) and 10 gender- and blood pressure-matched healthy controls (36±1 yrs, estimated GFR 102±5 ml/min, proteinuria 70±6 mg/d) were studied in high-salt balance. Blood pressure and arterial stiffness, expressed as pulse wave velocity and aortic augmentation index, were measured at baseline and in response to 60 min of angiotensin II (AngII) infusion.


RESULTS
At baseline, IgA nephropathy subjects demonstrated similar pulse wave velocity (8.6±0.7 vs. 8.0±0.4 m/s, p=0.5) but increased aortic augmentation index (12.6±3.1 vs. 1.8±4%, p=0.04) and a trend towards increased circulating renin-angiotensin system (RAS) components (plasma renin activity, 0.55±0.18 vs. 0.21±0.05 ng/l/s, p=0.08; angiotensin II, 25±5 vs. 16±1 ng/l, p=0.08) compared with controls. However, despite similar baseline blood pressure values (p=0.8), IgA nephropathy was associated with reduced arterial sensitivity to AngII challenge (Δmean arterial pressure: 19±4 vs. 29±1 mm Hg, p=0.05; Δpulse wave velocity: -0.06±0.6 vs. 1.5±0.3 m/s, p=0.07) compared with controls, even after multivariate analysis.


CONCLUSIONS
Even in the setting of early kidney disease, IgA nephropathy is associated with increased arterial stiffness and decreased angiotensin II responsiveness, a marker of increased RAS activity.
Department of Medicine, University of Calgary, Calgary, Canada.
A
A
Abdi-Ali
Department of Medicine, University of Calgary, Calgary, Canada Alberta Kidney Disease Network, Alberta, Canada.
M C
MC
Mann
Department of Medicine, University of Calgary, Calgary, Canada Alberta Kidney Disease Network, Alberta, Canada Libin Cardiovascular Institute of Alberta, Calgary, Canada.
B R
BR
Hemmelgarn
Department of Medicine, University of Calgary, Calgary, Canada Alberta Kidney Disease Network, Alberta, Canada Libin Cardiovascular Institute of Alberta, Calgary, Canada.
J M
JM
MacRae
Department of Medicine, University of Calgary, Calgary, Canada Alberta Kidney Disease Network, Alberta, Canada.
T C
TC
Turin
Department of Pathology, University of Calgary, Calgary, Canada.
H
H
Benediktsson
Department of Medicine, University of Calgary, Calgary, Canada Libin Cardiovascular Institute of Alberta, Calgary, Canada.
D Y
DY
Sola
Department of Medicine, University of Calgary, Calgary, Canada Alberta Kidney Disease Network, Alberta, Canada Libin Cardiovascular Institute of Alberta, Calgary, Canada sofia.ahmed@albertahealthservices.ca.
S B
SB
Ahmed
D000328:Adult; D000804:Angiotensin II / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D003971:Diastole / Q000187:drug effects; D005260:Female; D005922:Glomerulonephritis, IGA / Q000503:physiopathology*; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D063177:Pulse Wave Analysis; D012084:Renin-Angiotensin System / Q000187:drug effects; D059289:Vascular Stiffness / Q000187:drug effects
D000804:Angiotensin II
Angiotensin II; IgA nephropathy; arterial stiffness; blood pressure; human; renin angiotensin system