Gadolinium increases the vascular reactivity of rat aortic rings
Braz. j. med. biol. res
; 44(5): 445-452, May 2011. ilus, tab
Article
in English
| LILACS
| ID: lil-586508
Responsible library:
BR1.1
ABSTRACT
Gadolinium (Gd) blocks intra- and extracellular ATP hydrolysis. We determined whether Gd affects vascular reactivity to contractile responses to phenylephrine (PHE) by blocking aortic ectonucleoside triphosphate diphosphohydrolase (E-NTPDase). Wistar rats of both sexes (260-300 g, 23 females, 7 males) were used. Experiments were performed before and after incubation of aortic rings with 3 µM Gd. Concentration-response curves to PHE (0.1 nM to 0.1 mM) were obtained in the presence and absence of endothelium, after incubation with 100 µM L-NAME, 10 µM losartan, or 10 µM enalaprilat. Gd significantly increased the maximum response (control 72.3 ± 3.5; Gd 101.3 ± 6.4 percent) and sensitivity (control 6.6 ± 0.1; Gd 10.5 ± 2.8 percent) to PHE. To investigate the blockade of E-NTDase activity by Gd, we added 1 mM ATP to the bath. ATP reduced smooth muscle tension and Gd increased its relaxing effect (control -33.5 ± 4.1; Gd -47.4 ± 4.1 percent). Endothelial damage abolished the effect of Gd on the contractile responses to PHE (control 132.6 ± 8.6; Gd 122.4 ± 7.1 percent). L-NAME + Gd in the presence of endothelium reduced PHE contractile responses (control/L-NAME 151.1 ± 28.8; L-NAME + Gd 67.9 ± 19 percent AUC). ATP hydrolysis was reduced after Gd administration, which led to ATP accumulation in the nutrient solution and reduced ADP concentration, while adenosine levels remained the same. Incubation with Gd plus losartan and enalaprilat eliminated the pressor effects of Gd. Gd increased vascular reactivity to PHE regardless of the reduction of E-NTPDase activity and adenosine production. Moreover, the increased reactivity to PHE promoted by Gd was endothelium-dependent, reducing NO bioavailability and involving an increased stimulation of angiotensin-converting enzyme and angiotensin II AT1 receptors.
Full text:
Available
Collection:
International databases
Database:
LILACS
Main subject:
Aorta
/
Phenylephrine
/
Vasoconstriction
/
Vasodilation
/
Gadolinium
Limits:
Animals
Language:
English
Journal:
Braz. j. med. biol. res
Journal subject:
Biology
/
Medicine
Year:
2011
Document type:
Article
Affiliation country:
Brazil
Institution/Affiliation country:
Universidade Federal do Espírito Santo/BR
/
Universidade Federal do Rio Grande do Sul/BR