Selective renal vasoconstriction, exaggerated natriuresis and excretion rates of exosomic proteins in essential hypertension

• Published in: Acta Physiologica Vol. 212; no. 1; pp. 106 - 118
• Main Authors: Damkjær, M., Jensen, P. H., Schwämmle, V., Sprenger, R. R., Jacobsen, I. A., Jensen, O. N., Bie, P.
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01-09-2014; Wiley Subscription Services, Inc
• Subjects: Adult; Essential Hypertension; Exosomes - metabolism; hormones; Humans; hypertension; Hypertension - metabolism; Hypertension - physiopathology; kidney; Kidney - blood supply; Kidney - metabolism; Kidney - physiopathology; Kidney Function Tests; Male; Membrane Proteins - urine; Middle Aged; Natriuresis - physiology; Proteomics; renin; vascular resistance; Vasoconstriction; vascular resistance; kidney; proteomics; hormones; hypertension; renin
• ISSN: 1748-1708; 1748-1716
• DOI: 10.1111/apha.12345

Aim
In essential hypertension (EH), the regulation of renal sodium excretion is aberrant. We hypothesized that in mild EH, (i) abnormal dynamics of plasma renin concentration (PRC) and atrial natriuretic peptide (ANP) are responsible for the exaggerated natriuresis, and (ii) exosomic protein patterns reflect the renal tubular abnormality involved in the dysregulation of sodium excretion.
Methods
After 2‐week drug washout and 4‐day diet, systemic and renal hemodynamics, cardio‐renal hormones, glomerular filtration and renal excretion were studied in male patients during saline loading (SL). Excretion rates of exosome‐related urinary proteins including apical membrane transporters were determined by proteomics‐based methods.
Results
In patients, baseline renal vascular conductance was reduced (−44%, P < 0.001), but non‐renal vascular conductances were normal while PRC was reduced and ANP elevated (both P < 0.01). SL induced exaggerated natriuresis and reduced PRC (P < 0.01), at normal suppression rate. SL increased arterial pressure in patients (+11 mmHg, P < 0.001), but not in controls; however, during time control, patients showed identical increases (+10 mmHg, P < 0.005) apparently dissociating arterial pressure from natriuresis.
At baseline, excretion rates of 438 proteins ranged from 0.07 to 49.8 pmol (mmol creatinine)−1; 12 proteins were found in all subjects, and 21 proteins were found in two or more patients, but not in controls. In patients, the excretion rate of retinoic acid‐induced gene 2 protein was reduced, and excretion rates of other proteins showed increased variances compatible with pathophysiological and clinical applicability.
Conclusion
Essential hypertension patients exhibit selective renal vasoconstriction and individually varying excretion rates of several exosome‐related proteins. Hormonal changes, rather than arterial pressure, seem to cause exaggeration of natriuresis.