title: Central interaction between atrial natriuretic peptide and angiotensin II in the control of sodium intake and excretion in female rats.
abstract: We investigated the effects of estrogen on sodium intake and excretion induced by angiotensin II (ANG II), atrial natriuretic peptide (ANP) or ANG II plus ANP injected into the median nucleus (MnPO). Female Holtzman rats weighing 250-300 g were used. Sodium ingestion and excretion 120 min after the injection of 0.5 microliters of 0.15 M NaCl into the MnPO were 0.3 +/- 0.1 ml (N = 12) and 29 +/- 7 microEq in intact rats, 0.5 +/- 0.2 ml (N = 10) and 27 +/- 6 microEq in ovariectomized rats, and 0.2 +/- 0.08 (N = 11) and 36 +/- 8 microEq in estrogen-treated ovariectomized (50 micrograms/day for 21 days) rats, respectively. ANG II (21 microM) injection in intact, ovariectomized, and estrogen-treated ovariectomized rats increased sodium intake (3.8 +/- 0.4, 1.8 +/- 0.3 and 1.2 +/- 0.2 ml/120 min, respectively) (N = 11) and increased sodium excretion (166 +/- 18, 82 +/- 22 and 86 +/- 12 microEq/120 min, respectively) (N = 11). ANP (65 microM) injection in intact (N = 11), ovariectomized (N = 10) and estrogen-treated ovariectomized (N = 10) rats increased sodium intake (1.4 +/- 0.2, 1.8 +/- 0.3, and 1.7 +/- 0.3 ml/120 min, respectively) and sodium excretion (178 +/- 19, 187 +/- 9, and 232 +/- 29 microEq/120 min, respectively). Concomitant injection of ANG II and ANP into the MnPO of intact (N = 12), ovariectomized (N = 10) and estrogen-treated ovariectomized (N = 10) rats caused smaller effects than those produced by each peptide given alone: 1.3 +/- 0.2, 0.9 +/- 0.2 and 0.3 +/- 0.1 ml/120 min for sodium intake, respectively, and 86 +/- 9, 58 +/- 7, and 22 +/- 4 microEq/120 min for sodium excretion, respectively. Taken together, these results demonstrate that there is an antagonistic interaction of ANP and ANG II on sodium intake and excretion, and that reproductive hormones affect this interaction.
authors.affiliation: Departamento de Ciências Fisiológicas, Faculdade de Odontologia, Universidade Estadual Paulista, Araraquara, SP, Brasil.
authors.forename: P R
authors.initials: PR
authors.lastname: De-Angelis
authors.forename: V R
authors.initials: VR
authors.lastname: Antunes
authors.forename: G M
authors.initials: GM
authors.lastname: Camargo
authors.forename: W A
authors.initials: WA
authors.lastname: Saad
authors.forename: A
authors.initials: A
authors.lastname: Renzi
authors.forename: L A
authors.initials: LA
authors.lastname: Camargo
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D010052:Ovariectomy; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000652:urine*; D017673:Sodium Chloride, Dietary / Q000008:administration & dosage*
chemical_list: D004967:Estrogens; D017673:Sodium Chloride, Dietary; D000804:Angiotensin II; D009320:Atrial Natriuretic Factor; D012964:Sodium