title: Effect of intraperitoneally administered hydrolyzed whey protein on blood pressure and renal sodium handling in awake spontaneously hypertensive rats.
abstract: The present study evaluated the acute effect of the intraperitoneal (ip) administration of a whey protein hydrolysate (WPH) on systolic arterial blood pressure (SBP) and renal sodium handling by conscious spontaneously hypertensive rats (SHR). The ip administration of WPH in a volume of 1 ml dose-dependently lowered the SBP in SHR 2 h after administration at doses of 0.5 g/kg (0.15 M NaCl: 188.5 +/- 9.3 mmHg vs WPH: 176.6 +/- 4.9 mmHg, N = 8, P = 0.001) and 1.0 g/kg (0.15 M NaCl: 188.5 +/- 9.3 mmHg vs WPH: 163.8 +/- 5.9 mmHg, N = 8, P = 0.0018). Creatinine clearance decreased significantly (P = 0.0084) in the WPH-treated group (326 +/- 67 microL min-1 100 g body weight-1) compared to 0.15 M NaCl-treated (890 +/- 26 microL min-1 100 g body weight-1) and captopril-treated (903 +/- 72 microL min-1 100 g body weight-1) rats. The ip administration of 1.0 g WPH/kg also decreased fractional sodium excretion to 0.021 +/- 0.019% compared to 0.126 +/- 0.041 and 0.66 +/- 0.015% in 0.15 M NaCl and captopril-treated rats, respectively (P = 0.033). Similarly, the fractional potassium excretion in WPH-treated rats (0.25 +/- 0.05%) was significantly lower (P = 0.0063) than in control (0.91 +/- 0.15%) and captopril-treated rats (1.24 +/- 0.30%), respectively. The present study shows a decreased SBP in SHR after the administration of WPH associated with a rise in tubule sodium reabsorption despite an angiotensin I-converting enzyme (ACE)-inhibiting in vitro activity (IC50 = 0.68 mg/mL). The present findings suggest a pathway involving ACE inhibition but measurements of plasma ACE activity and angiotensin II levels are needed to support this suggestion.
authors.affiliation: Departamento de Planejamento Alimentar e Nutrição, Faculdade de Engenharia de Alimentos, Universidade Estadual de Campinas, 13083-970 Campinas, SP, Brazil.
authors.forename: E L
authors.initials: EL
authors.lastname: Costa
authors.forename: A R
authors.initials: AR
authors.lastname: Almeida
authors.forename: F M
authors.initials: FM
authors.lastname: Netto
authors.forename: J A R
authors.initials: JA
authors.lastname: Gontijo
mesh_terms: D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002216:Captopril / Q000494:pharmacology; D019075:Electrophoresis, Capillary; D007677:Kidney Function Tests; D008297:Male; D008894:Milk Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D011188:Potassium / Q000652:urine; D011492:Protein Hydrolysates / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D011918:Rats, Inbred SHR; D012964:Sodium / Q000652:urine; D000067816:Whey Proteins
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D008894:Milk Proteins; D011492:Protein Hydrolysates; D000067816:Whey Proteins; D002216:Captopril; D012964:Sodium; D011188:Potassium