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Effect of mild hyperisulinemia on conduit vessel endothelial function: role of noradrenergic activation.
MedLine Citation:
PMID:  22245986     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
OBJECTIVE:: The evidence that an exogenously induced modest hyperinsulinemia deteriorates conductance artery endothelial function - flow-mediated dilatation (FMD) - in healthy individuals is in contrast with in-vitro and in-vivo studies that consistently found that insulin facilitates both nitric oxide release and the endothelium-dependent dilatation. The aim of this study was to verify whether this effect is caused by the enhancement of insulin-induced adrenergic tone. METHOD:: In 10 healthy male volunteers, endothelium-dependent (FMD) and endothelium-independent (glyceryl trinitrate, GTN) dilatation were evaluated by high-resolution ultrasound of the brachial artery, combined with a computerized edge detection system, at baseline (-60 and 0 min) and after 120 and 240 min during insulin infusion (INS study). In five participants, randomly selected from the initial group, the study was repeated during an isotonic saline (0.9% sodium chloride) intravenous infusion (SAL study). In an additional five participants, insulin infusion was preceded by an intravenous infusion of clonidine started 40 min before insulin and continued throughout the study (INS + CLN study). RESULTS:: Plasma norepinephrine concentration increased in the INS study from 260 ± 40 to 333 ± 62 pg/ml (P < 0.05), whereas it remained stable throughout the INS + CLN study. In the INS study, no change in FMD was observed, whereas the response to GTN tended to decrease (P = 0.09). In the INS + CLN study, no significant changes in FMD response were observed, whereas GTN response was completely restored. CONCLUSION:: Physiological hyperinsulinemia has no effect on endothelium-dependent vasodilatation in conduit vessels of healthy individuals, but it induces a slight decline in endothelium-independent vasodilatation, which is entirely explained by the insulin-induced noradrenergic activation.
Authors:
Cecilia Morgantini; Francesco Stea; Beatrice Boldrini; Emiliano Duranti; Lorenzo Ghiadoni; Andrea Natali
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-1-12
Journal Detail:
Title:  Journal of hypertension     Volume:  -     ISSN:  1473-5598     ISO Abbreviation:  -     Publication Date:  2012 Jan 
Date Detail:
Created Date:  2012-1-16     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8306882     Medline TA:  J Hypertens     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
aMetabolism and Hypertension Units, Department of Internal Medicine, University of Pisa bScuola Superiore Sant'Anna, Pisa, Italy.
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