title: Weight loss, saline loading, and the natriuretic peptide system.
abstract: BACKGROUND
  In epidemiologic studies, obesity has been associated with reduced natriuretic peptide (NP) concentrations. Reduced NP production could impair the ability of obese individuals to respond to salt loads, increasing the risk of hypertension and other disorders. We hypothesized that weight loss enhances NP production before and after salt loading.
  
  
  RESULTS
  We enrolled 15 obese individuals (mean BMI 45±5.4 kg/m(2)) undergoing gastric bypass surgery. Before and 6 months after surgery, subjects were admitted to the clinical research center and administered a large-volume intravenous saline challenge. Echocardiography and serial blood sampling were performed. From the pre-operative visit to 6 months after surgery, subjects had a mean BMI decrease of 27%. At the 6-month visit, N-terminal pro-atrial NP (Nt-proANP) levels were 40% higher before, during, and after the saline infusion, compared with levels measured at the same time points during the pre-operative visit (P<0.001). The rise in Nt-pro-ANP induced by the saline infusion (≈50%) was similar both before and after surgery (saline, P<0.001; interaction, P=0.2). Similar results were obtained for BNP and Nt-proBNP; resting concentrations increased by 50% and 31%, respectively, after gastric bypass surgery. The increase in NP concentrations after surgery was accompanied by significant decreases in mean arterial pressure (P=0.004) and heart rate (P<0.001), and an increase in mitral annular diastolic velocity (P=0.02).
  
  
  CONCLUSIONS
  In obese individuals, weight loss is associated with a substantial increase in the "setpoint" of circulating NP concentrations. Higher NP concentrations could contribute to an enhanced ability to handle salt loads after weight loss.
authors.affiliation: Cardiology Division, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL (P.A.).
authors.forename: Pankaj
authors.initials: P
authors.lastname: Arora
authors.affiliation: Atlanta Cardiology and Primary Care, Saint Joseph's Research Institute, Atlanta, GA (J.R.).
authors.forename: Jason
authors.initials: J
authors.lastname: Reingold
authors.affiliation: Division of Cardiology, Massachusetts General Hospital, Boston, MA (A.B., D.P.G., A.G., M.J.S., K.D.B., M.S.C., C.N.C.).
authors.forename: Aaron
authors.initials: A
authors.lastname: Baggish
authors.affiliation: Division of Cardiology, Massachusetts General Hospital, Boston, MA (A.B., D.P.G., A.G., M.J.S., K.D.B., M.S.C., C.N.C.).
authors.forename: Derek P
authors.initials: DP
authors.lastname: Guanaga
authors.affiliation: Department of Anesthesia, Critical Care & Pain Medicine, Massachusetts General Hospital, Boston, MA (C.W., L.T.T., E.S.B., K.D.B.).
authors.forename: Connie
authors.initials: C
authors.lastname: Wu
authors.affiliation: Division of Cardiology, Massachusetts General Hospital, Boston, MA (A.B., D.P.G., A.G., M.J.S., K.D.B., M.S.C., C.N.C.).
authors.forename: Anahita
authors.initials: A
authors.lastname: Ghorbani
authors.affiliation: Department of Biostatistics, Vanderbilt University, Nashville, TN (Y.S.).
authors.forename: Yanna
authors.initials: Y
authors.lastname: Song
authors.affiliation: Division of Cardiology, Jewish General Hospital, Montreal, Quebec, Canada (A.C.T.).
authors.forename: Annabel
authors.initials: A
authors.lastname: Chen-Tournaux
authors.affiliation: Division of Cardiovascular Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA (A.M.K.).
authors.forename: Abigail May
authors.initials: AM
authors.lastname: Khan
authors.affiliation: Department of Anesthesia, Critical Care & Pain Medicine, Massachusetts General Hospital, Boston, MA (C.W., L.T.T., E.S.B., K.D.B.).
authors.forename: Laurel T
authors.initials: LT
authors.lastname: Tainsh
authors.affiliation: Department of Anesthesia, Critical Care & Pain Medicine, Massachusetts General Hospital, Boston, MA (C.W., L.T.T., E.S.B., K.D.B.).
authors.forename: Emmanuel S
authors.initials: ES
authors.lastname: Buys
authors.affiliation: Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, Brigham & Women's Hospital, Boston, MA (J.S.W.).
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Williams
authors.affiliation: Division of Cardiology, Mayo Clinic, Rochester, MN (D.M.H., J.C.B.).
authors.forename: Denise M
authors.initials: DM
authors.lastname: Heublein
authors.affiliation: Division of Cardiology, Mayo Clinic, Rochester, MN (D.M.H., J.C.B.).
authors.forename: John C
authors.initials: JC
authors.lastname: Burnett
authors.affiliation: Division of Cardiology, Massachusetts General Hospital, Boston, MA (A.B., D.P.G., A.G., M.J.S., K.D.B., M.S.C., C.N.C.).
authors.forename: Marc J
authors.initials: MJ
authors.lastname: Semigran
authors.affiliation: Division of Cardiology, Massachusetts General Hospital, Boston, MA (A.B., D.P.G., A.G., M.J.S., K.D.B., M.S.C., C.N.C.) Department of Anesthesia, Critical Care & Pain Medicine, Massachusetts General Hospital, Boston, MA (C.W., L.T.T., E.S.B., K.D.B.).
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Bloch
authors.affiliation: Division of Cardiology, Massachusetts General Hospital, Boston, MA (A.B., D.P.G., A.G., M.J.S., K.D.B., M.S.C., C.N.C.).
authors.forename: Marielle
authors.initials: M
authors.lastname: Scherrer-Crosbie
authors.affiliation: Division of Cardiology, Massachusetts General Hospital, Boston, MA (A.B., D.P.G., A.G., M.J.S., K.D.B., M.S.C., C.N.C.).
authors.forename: Christopher
authors.initials: C
authors.lastname: Newton-Cheh
authors.affiliation: Gastrointestinal Unit, Department of Medicine, Massachusetts General Hospital, Boston, MA (L.M.K.).
authors.forename: Lee M
authors.initials: LM
authors.lastname: Kaplan
authors.affiliation: Division of Cardiovascular Medicine, Vanderbilt University, Nashville, TN (T.J.W.).
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Wang
mesh_terms: D000328:Adult; D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000517:prevention & control; D015331:Cohort Studies; D015150:Echocardiography, Doppler; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D015390:Gastric Bypass / Q000379:methods; D006801:Humans; D006973:Hypertension / Q000517:prevention & control; D007262:Infusions, Intravenous; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D020097:Natriuretic Peptide, Brain / Q000097:blood* / Q000378:metabolism; D009767:Obesity, Morbid / Q000097:blood* / Q000175:diagnosis / Q000601:surgery*; D010446:Peptide Fragments / Q000097:blood* / Q000378:metabolism; D011182:Postoperative Care / Q000379:methods; D011300:Preoperative Care / Q000379:methods; D011379:Prognosis; D012965:Sodium Chloride / Q000008:administration & dosage*; D015431:Weight Loss
chemical_list: D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain; D012965:Sodium Chloride
keywords: natriuretic peptide; obesity; salt intake