Des-serine-proline brain natriuretic peptide 3-32 in cardiorenal regulation

1 Cardiorenal Research Laboratory, Mayo Clinic and Mayo Clinic College of Medicine, Rochester, Minnesota; and 2 Department of Cardiology, Helios-Klinikum, Erfurt, Germany Submitted 9 August 2006 ; accepted in final form 21 October 2006 Brain natriuretic peptide (BNP 1–32) plays an important physiologic role in cardiorenal homeostasis. Recently, it has been reported that BNP 1–32 is rapidly cleaved by the ubiquitous enzyme dipeptidyl peptidase IV to BNP 3–32, which lacks the two NH 2 -terminal amino acids of BNP 1–32. The bioactivity of BNP 3–32 in cardiorenal regulation is unknown. We hypothesized that BNP 3–32 has reduced vasodilating and natriuretic bioactivity compared with BNP 1–32 in vivo. Synthetic human BNP 3–32 and BNP 1–32 were administered to eight anesthetized normal canines. After baseline measurements, BNP 1–32 at 30 ng·kg –1 ·min –1 was administered, followed by a washout, a postinfusion clearance, and a clearance with an equimolar dose of BNP 3–32. In four studies, the sequence of BNP 1–32 and BNP 3–32 infusion was reversed. Peptides were compared by analyzing the changes from the respective preinfusion clearance to the respective infusion clearance. * P < 0.05 between peptides. BNP 3–32, unlike BNP 1–32, did not decrease mean arterial pressure (0 ± 1 vs. –7 ± 2* mmHg, respectively) and did not increase renal blood flow (+12 ± 10 vs. +52 ± 10* ml/min). Effects on heart rate and cardiac output were similar. Urinary sodium excretion increased 128 ± 18 µeq/min with BNP 3–32 and 338 ± 40* µeq/min with BNP 1–32. Urine flow increased 1.1 ± 0.2 ml/min with BNP 3–32 and 2.8 ± 0.4* ml/min with BNP 1–32. Plasma BNP immunoreactivity was lower with BNP 3–32, suggesting accelerated degradation. In this study, BNP 3–32 showed reduced natriuresis and diuresis and a lack of vasodilating actions compared with BNP 1–32. hormone; enzymatic degradation product; cardiorenal regulation; BNP 3–32 Address for reprint requests and other correspondence: G. Boerrigter, Cardiorenal Research Laboratory, Guggenheim 915, Mayo Clinic and Mayo Clinic College of Medicine, 200 First St. SW, Rochester, MN 55905 (e-mail: boerrigter.guido{at}mayo.edu )