Renal sodium handling after noradrenergic stimulation of the lateral hypothalamic area in rats.
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.
Gontijo
J A
JA
Departamento de Clínica Médica, Núcleo de Medicina e Cirurgia Experimental, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, SP, Brasil.
Garcia
W E
WE
Figueiredo
J F
JF
Silva-Netto
C R
CR
Furtado
M R
MR
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
D011941:Receptors, Adrenergic; D012964:Sodium; D003404:Creatinine; D018021:Lithium Chloride; D011188:Potassium; D009638:Norepinephrine