The pre‐exposure to nitric oxide donor ([Ru(terpy)(bdq)NO]3
            3
            )TERPY induced tolerance endothelium‐dependent in Wistar rats and SHR aortas (851.9)

Leptomeningeal anastomoses (LMAs) are pial collaterals that perfuse the penumbra and important for stroke outcome. We previously showed LMAs from SHRs (spontaneously hypertensive rats) were vasoconstricted compared with normotensive Wistar rats. Here, we investigated mechanisms by which hypertension causes LMA vasoconstriction. SHRs were treated with the ACE (angiotensin-converting enzyme) inhibitor captopril, an Ang II (angiotensin II)–independent antihypertensive agent hydralazine, or vehicle for 5 weeks in drinking water (n=8/group). A group of Wistar rats (n=8) had regular drinking water served as controls. Blood pressure was measured twice weekly by tail-cuff. LMAs were isolated and studied under pressurized conditions. Vasoreactivity of LMAs, including myogenic responses, reactivity to Rho-kinase inhibitor Y-27632, and nitric oxide were measured. Both captopril and hydralazine lowered blood pressure in SHRs similar to Wistar. However, only captopril normalized LMA increased tone compared with untreated SHRs (15±2% versus 50±3%; P <0.01) that was similar to Wistar (16±2%) but not hydralazine (38±6%; P >0.05). Vasodilatory response of LMAs to Y-27632 was impaired in SHRs compared with Wistar (28±3% versus 81±4%; P <0.01) that was restored by captopril (84±5%; P <0.01) and partially hydralazine (59±4%). LMAs from all groups constricted similarly to NOS (NO synthase) inhibition; however, the vasodilatory response of LMAs to the nitric oxide donor sodium nitroprusside was impaired in SHRs compared with Wistar rats (29±4% versus 80±2%; P <0.01) that was restored by captopril (84±4%; P <0.01), not hydralazine (38±8%; P >0.05). These results suggest that ACE inhibition during chronic hypertension reversed vascular dysfunction and hyperconstriction of LMAs that could improve stroke outcome by increasing collateral perfusion.

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Effects of Rut-bpy (Cis-[Ru(bpy)2(SO3)(NO)]PF 6), a novel nitric oxide donor, in L-NAME-induced hypertension in rats

Acta Cirurgica Brasileira ◽

10.1590/s0102-86502011000700012 ◽

2011 ◽

Vol 26 (suppl 1) ◽

pp. 57-59 ◽

Cited By ~ 3

Author(s):

Marcio Wilker Soares Campelo ◽

Ana Paula Bomfim Soares Campelo ◽

Luiz Gonzaga de França Lopes ◽

Armenio Aguiar dos Santos ◽

Sergio Botelho Guimarães ◽

...

Keyword(s):

Nitric Oxide ◽

Blood Pressure ◽

Methyl Ester ◽

Arterial Blood Pressure ◽

Wistar Rats ◽

Nitric Oxide Donor ◽

Hypertensive Rats ◽

Arterial Blood ◽

Induced Hypertension ◽

Male Wistar Rats

PURPOSE: To evaluate the effect of Rut-bpy (Cis-[Ru(bpy)2(SO3)(NO)]PF 6), a novel nitric oxide donor in Nω-nitro-L-arginine methyl ester (L-NAME)-induced hypertensive rats. METHODS: Twenty-four male Wistar rats were randomly assigned to four groups (n=6), named according to the treatment applied (G1-Saline, G2-Rut-bpy, G3-L-NAME and G4-L-NAME+Rut-bpy). L-NAME (30 mg/Kg) was injected intraperitoneally 30 minutes before the administration of Rut-bpy (100 mg/Kg). Mean abdominal aorta arterial blood pressure (MAP) was continuously monitored. RESULTS: Mean arterial blood pressure (MAP) in G3 rats rose progressively, reaching 147±16 mmHg compared with 100±19 mm Hg in G1 rats (p<0.05). In G4 rats, treated with L-NAME+Rut-bpy, MAP reached 149+11 mm Hg while in G2 rats, treated with Rut-bpy, MAP values were 106±11 mm Hg. In G1 rats these values decreased progressively reaching 87+14 mm Hg after 30 minutes. An important finding was the maintenance of the MAP throughout the experiment in G2 rats. CONCLUSION: Rut-bpy does not decrease the MAP in L-Name induced hypertensive rats. However, when it is used in anesthetized hypotensive rats a stable blood pressure is obtained.

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