Enhanced urinary excretion of albumin and β2 microglobulin in essential hypertension induced by atrial natriuretic peptide

Atrial natriuretic peptide (ANP) was given as an intravenous bolus injection (2.0 µg kg-1) to 12 essential hypertensive patients (EH) and 10 normotensive control subjects (C) in order to study the effect of ANP on urinary excretion of albumin and β2-microglobulin, and on glomerular filtration rate (GFR), renal plasma flow (RPF), and filtration fraction (FF). After the ANP injection, urinary excretion of albumin increased significantly (p<0.01) in EH from 7.3 µg min to 125 µg min (medians) and in C from 2.9 µg min-1 to 8.1 µg min -1 (p<0.05). Urinary excretion of β2-microglobulin increased in EH from 70 ng min-1 to 1022 ng min-1 (p<0.01) and in C from 118 ng min-1 to 170 ng min-1 (p<0.01). The increase in urinary excretion of both albumin (p<0.01) and B2-microglobulin (p<0.01) was significantly more pronounced in EH than in C. GFR and RPF were almost unchanged in both groups. FF rose to the same degree in the two groups. The increase in fractional excretion of sodium and in urine volume after ANP was enhanced in EH. It is concluded that ANP in pharmacological doses increased urinary excretion of albumin and β2-microglobulin to a considerably larger extent in essential hypertensive patients than in normotensive control subjects.