title: Renal sodium handling after noradrenergic stimulation of the lateral hypothalamic area in rats.
abstract: 1. The participation of special nephron segments in the renal control of sodium handling after adrenergic stimulation was investigated by determining lithium clearance in groups of 5-12 male Wistar rats (230-300 g) microinjected with noradrenaline into the lateral hypothalamic area (LHA). 2. Microinjection of noradrenaline (12.5 to 100.0 nmol/microliters) into the LHA promoted a significant decrease in proximal sodium reabsorption (controls, 86.5 +/- 1.3; 12.5, 81.4 +/- 2.0; 25.0, 72.6 +/- 2.4; 50.0, 75.4 +/- 1.8 and 100.0, 77.2 +/- 1.7%) and a dose-related increase in distal sodium reabsorption (control, 13.4 +/- 1.6; 12.5, 18.4 +/- 1,25.0, 26.9 +/- 2.9; 50.0, 24.1 +/- 2.7; 100.0, 22.1 +/- 1.9%) with no significant changes in creatinine clearance. Fractional sodium reabsorption after different noradrenaline concentrations was significantly reduced in the proximal nephron sites up to the concentration of 25.0 nmol/microliter. Beyond this concentration, a smaller but progressive increase in fractional sodium reabsorption was observed in the post-proximal segment. 3. These findings suggest an effective participation of proximal and post-proximal nephrons in natriuresis after lateral hypothalamic noradrenergic stimulation.
authors.affiliation: Departamento de Clínica Médica, Núcleo de Medicina e Cirurgia Experimental, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, SP, Brasil.
authors.forename: J A
authors.initials: JA
authors.lastname: Gontijo
authors.forename: W E
authors.initials: WE
authors.lastname: Garcia
authors.forename: J F
authors.initials: JF
authors.lastname: Figueiredo
authors.forename: C R
authors.initials: CR
authors.lastname: Silva-Netto
authors.forename: M R
authors.initials: MR
authors.lastname: Furtado
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D003404:Creatinine / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D007026:Hypothalamic Area, Lateral / Q000187:drug effects* / Q000502:physiology; D007668:Kidney / Q000187:drug effects* / Q000502:physiology; D018021:Lithium Chloride / Q000032:analysis; D008297:Male; D008845:Microinjections; D009318:Natriuresis / Q000187:drug effects*; D009638:Norepinephrine / Q000008:administration & dosage / Q000494:pharmacology; D011188:Potassium / Q000032:analysis; D051381:Rats; D011941:Receptors, Adrenergic / Q000187:drug effects* / Q000502:physiology; D012964:Sodium / Q000032:analysis; D013268:Stimulation, Chemical
chemical_list: D011941:Receptors, Adrenergic; D012964:Sodium; D003404:Creatinine; D018021:Lithium Chloride; D011188:Potassium; D009638:Norepinephrine