Mannitol Stimulates Atrial Natriuretic Peptide Release in Humans

The purpose of this study was to determine if mannitol stimulates atrial natriuretic peptide (ANP) release in humans and to examine potential mechanisms for this effect. Twenty patients requiring cardiac catheterization were randomized to receive either mannitol (15-g bolus followed by 15% infusion mixed in 75 mmol/L saline at 100 mL/h for 1 hour) or an equal volume of 75 mmol/L saline, intravenously (IV). All measurements were made at three time points: at baseline, at 10 minutes (after the bolus but before radiocontrast administration), and at 60 minutes (after completion of the study). Baseline plasma ANP (P_ANP) measurements (mean ± SE) were similar in both groups (saline, 73 ± 38 pg/mL; mannitol, 62 ± 11 pg/mL). P_ANP increased significantly over time for the set of all patients (analysis of variance [ANOVA], P< 0.05); however, at 10 minutes P_ANP increased significantly only in the group receiving mannitol (saline, 76 ± 43 pg/mL; mannitol, 100 ± 29 pg/mL) (P<0.04). Serum osmolality (S_OSM), plasma antidiuretic hormone (P_ADH) levels, and right atrial and pulmonary wedge pressures increased significantly over time for the set of all patients (ANOVA, P<0.04). At 10 minutes there were significant increases only in the group receiving mannitol, and after radiocontrast, there were significant increases in both groups for all parameters. Regression analysis demonstrated a significant correlation between the change in P_ANP and the change in S_OSM (P<0.04, r = 0.33). In conclusion, intravascular infusion of mannitol or radiocontrast increased P_ANP levels. The mechanism may be multifactorial, with a potential role for an increase in S_OSM and/or P_ADH.