Haemodynamic and renal effects of urodilatin in healthy volunteers

Urodilatin (ANF(95-126)), an analogue of the atrial natriuretic factor (ANF(99-126)), has recently been isolated from human urine. To study haemodynamic and renal effects of synthetic urodilatin, 18 healthy male volunteers (age 26.1 +/- 0.8 years; X +/- SEM) received i.v. bolus injections of urodilatin at doses of 1, 2 or 4 micrograms kg-1 body weight (bw) (n = 6 per dosage group). Urodilatin dose-dependently increased heart rate and cardiac index. A dose-dependent increase in plasma cyclic GMP levels was also observed. Urinary cyclic GMP excretion, urine flow and natriuresis increased 7-fold, 5-fold and 4-fold, respectively. Renal effects were not different between dosage groups. Compared with ANF(99-126), after urodilatin the reduction in mean pulmonary arterial pressure (PAP) was more pronounced (2 micrograms kg-1, n = 6; ANF -1.8 +/- 0.5, URO: -5.5 +/- 1.1 mmHg, P less than 0.05). Furthermore, after urodilatin the reduction of PAP lasted continuously from 2 up to 90 min after injection, while ANF(99-126) produced only a transient decrease of PAP. Similarly the reduction of pulmonary capillary wedge pressure (PCWP) by urodilatin from 9.3 +/- 1.2 to 3.8 +/- 0.9 mmHg (P less than 0.05) was also sustained up to 90 min post administration. These data in healthy volunteers suggest that, due to prolonged reduction of PAP and PCWP with increases of cardiac index and reduction of systemic vascular resistance, urodilatin might exhibit beneficial effects in cardiovascular disease.