Sodium load combined with low doses of exogenous angiotensin II upregulate intrarenal angiotensin II.
OBJECTIVE
The present study was designed to evaluate the effects of a salt load combined with exogenous low nonhypertensive angiotensin II (Ang II) doses on Ang II intrarenal regulation.


METHODS
Sprague-Dawley rats were infused with Ang II nonhypertensive doses (0.1 microg.kg(-1).h(-1) and 5 microg.kg(-1).h(-1)) and saline overload (Na 0.5 M, Na 1.0 M and Na 1.5 M) for 2 h (0.04 ml.min(-1)). Sodium tubular reabsorption, sodium urinary excretion and mean arterial pressure (MAP) were measured. Ang II was evaluated in the kidneys by immunohistochemistry.


RESULTS
Ang II levels in glomeruli and vessels were exacerbated when sodium load and Ang II were given simultaneously, independently of MAP elevation. In tubules, Ang II staining in the presence of sodium overload was greater in the Ang 0.1 groups than in the Ang 5 groups. Compared with the controls, sodium tubular reabsorption rose in the Ang 0.1-Na 0.5 and Ang 0.1-Na 1 groups and sodium urinary excretion decreased in the Ang 5-Na 0.5 and Ang 5-Na 1 groups. MAP increased in the Ang 5-Na 1 and Ang 5-Na 1.5 groups.


CONCLUSIONS
We conclude that local renal Ang II levels were upregulated when acute sodium overload and nonhypertensive Ang II doses were administered simultaneously in normal rats, independently from blood pressure and glomerular function changes.
Rosón
María Inés
MI
Department of Pathophysiology, Faculty of Pharmacy and Biochemistry, University of Buenos Aires, INFIBIOC-CONICET, Buenos Aires, Argentina. iroson@ffyb.uba.ar
Cao
Gabriel
G
Della Penna
Silvana
S
Gorzalczany
Susana
S
Pandolfo
Marcela
M
Medici
Cecilia
C
Fernández
Belisario E
BE
Toblli
Jorge E
JE
D000804:Angiotensin II / Q000378:metabolism* / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005919:Glomerular Filtration Rate / Q000187:drug effects; D007668:Kidney / Q000187:drug effects* / Q000378:metabolism*; D008297:Male; D023421:Models, Animal; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000494:pharmacology* / Q000652:urine; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014882:Water-Electrolyte Balance / Q000187:drug effects
D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D012964:Sodium