Consequences of cerebroventricular insulin injection on renal sodium handling in rats: effect of inhibition of central nitric oxide synthase
Braz. j. med. biol. res
;
42(12): 1196-1202, Dec. 2009. ilus, tab
Article
in English
| LILACS
| ID: lil-532292
ABSTRACT
In the present study, we investigated the effects of acute intracerebroventricular (icv) insulin administration on central mechanisms regulating urinary sodium excretion in simultaneously centrally NG-nitro-L-arginine methylester (L-NAME)-injected unanesthetized rats. Male Wistar-Hannover rats were randomly assigned to one of five groups a) icv 0.15 M NaCl-injected rats (control, N = 10), b) icv dose-response (1.26, 12.6 and 126 ng/3 µL) insulin-injected rats (N = 10), c) rats icv injected with 60 µg L-NAME in combination with NaCl (N = 10) or d) with insulin (N = 10), and e) subcutaneously insulin-injected rats (N = 5). Centrally administered insulin produced an increase in urinary output of sodium (NaCl 855.6 ± 85.1 Ä percent/min; 126 ng insulin 2055 ± 310.6 Ä percent/min; P = 0.005) and potassium (NaCl 460.4 ± 100 Ä percent/min; 126 ng insulin 669.2 ± 60.8 Ä percent/min; P = 0.025). The urinary sodium excretion response to icv 126 ng insulin microinjection was significantly attenuated by combined administration of L-NAME (126 ng insulin 1935 ± 258.3 Ä percent/min; L-NAME + 126 ng insulin 582.3 ± 69.6 Ä percent/min; P = 0.01). Insulin-induced natriuresis occurred by increasing post-proximal sodium excretion, despite an unchanged glomerular filtration rate. Although the rationale for decreased urinary sodium excretion induced by combined icv L-NAME and insulin administration is unknown, it is tempting to suggest that perhaps one of the efferent signals triggered by insulin in the CNS may be nitrergic in nature.
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Index:
LILACS (Americas)
Main subject:
Brain
/
Nitric Oxide Synthase
/
Insulin
/
Natriuresis
Limits:
Animals
Language:
English
Journal:
Braz. j. med. biol. res
Journal subject:
Biology
/
Medicine
Year:
2009
Type:
Article
/
Project document
Affiliation country:
Brazil
Institution/Affiliation country:
Universidade Estadual de Campinas/BR
/
Universidade Federal de Uberlândia/BR
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