[Effects of chronic volume loading on atrial natriuretic peptide release in human]

In the present study, we investigated whether release of hANP increases during mild and long-term volume loading. Eight lung cancer patients in good performance state (five men and three women, 35 to 68 years), who needed to have pre-hydration for cancer chemotherapy with cisplatin, were infused with about seven liters of isotonic saline over 48 hours through Swan-Ganz catheter placed in the pulmonary artery. The mean infusion rate was 0.042 ml/min.kg body weight. During the infusion, change in plasma volume (delta PV) increased by 5.8 + 3.3 (mean +/- SE) %. Right atrial pressure (RAP) did not change significantly, and pulmonary artery wedge pressure (PAWP) increased from 4.3 +/- 1.0 to 5.8 +/- 0.7 mmHg. Plasma hANP was significantly elevated from 50.6 +/- 0.7 to 105.1 +/- 19.3 pg/ml by the second day of the infusion with a suppression of plasma renin activity (PRA) and aldosterone, though plasma ADH did not change. The infusion rate at 20:00 on the first day was the same as that on the second day. Further increase in plasma hANP was shown at 20:00 on the second day compared with the level at the same time on the first day, though RAP, PAWP and delta PV did not change. These results indicate that mild and chronic volume loading increases plasma hANP, and suggest that the prolongation of volume expansion plays an important role in the releasing of hANP in humans.